E I. E M B N T S 



AaEICULTURAL CHEMISTRY 



AND 



GEOLOGY. 



BY 



JAxMES F. IV/ JOHNSTON, M.A,, F.RSS. L. & E. 

Honorary Member of the Royal Agricultural Society of England, and 
Author of " Lectures on Agricultural Chemistry and Geology." 



WITH A COMPLETE INDEX, 



AMERICAN PREFACE: 

BY SIMON BROWN, ^ ^. . . . , 

FDITOR OF THF NEW ENGLAND FARMER. >_^. A 

NEW YORK: "" : ^,,! --" 

C. 31. S AXTOIT, 

AGRICULTURAL BOOK PUBLISHER. 
1853. 



Enlered according to Act of Congress, in the j-ear 1S53, hy 

C. M. SAXTOX, 

in the Clerk's Office of the District Court of the United States for Iho South- 
ern District of New York. 



S. W. BENEDICT, 
Sterkotyper and Printer, 
16 Spruce slrenl, N. Y. 






PREFACE TO THE AMERICAN EDITION. 



In England, and on the continent of Europe, it has been 
long understood among the class who own the soil, and culti^ 
vate it by the sweat of the brow of other men, and not their 
personal labor, that success in husbandry must depend upon 
giving to the soil, in some form, what is annually taken away 
in cultivated crops. 

In America, in the older States, the same truth is at length 
reluctantly admitted. The census tables have shown that the 
wheat crop of New York, in some counties, has fallen in its 
average product so low as eight bushels to the acre, where for- 
merly from thirty to forty were produced. Lands deemed inex- 
haustible have been cropped almost to barrenness. Large sec- 
tions of territory in Virginia, formerly very productive, by a 
course of culture not guided by a correct knowledge of the 
science of Husbandry, have become utterly unproductive, and 
been abandoned by the original cultivators. A succession of 
tobacco crops raised by shoal plowing without artificial manur- 
ing, or a proper rotation with other products, exhausted the 
surface soil, and compelled^^ the proprietors to seek fresh fields. 
Recently a more thorough and intelligent system, by men who 
are both owners of the land and laborers upon it, has shown 
that it was only with mireasonahle demands upon her resources 



PREFACE. 



that a generous mother Earth had refused to comply; for the 
same lands, by deep plowing and judicious rotation, are yielding 
already a rich return for labor and capital to their owners.. 

In both countries it is now regarded by well-informed men as 
settled, that only labor directed by scientific knowledge can 
yield a fair return upon any but new lands, where, as in our 
Western States, Nature's storehouses of fertilizers are yet unex- 
hausted. In England the soil is owned by a few, and those 
mostly educated men, and they, directly or indirectly, insist 
upon systematic and thorough tillage, as the only means of 
deriving profit from their capital. 

In America, in the free States, the land owner labors with 
his own hands, and a' knowledge of the principles of husbandry 
must be generally diffused, that each for himself may apply 
them in his own practice. Indeed, it seems peculiarly fitting 
that the owner of the soil, who himself performs the labor upon 
it, should have constantly in view the reason for the various 
processes he performs in bringing his crops to maturity. 

No writer, perhaps, of the present day, has succeeded so 
well as Mr. Johnston, in adapting to the apprehension of the 
general reader his teachingsHipon the Science of Agriculture, — ■ 
in combining with instructions necessarily abstruse, the practi- 
cal ideas which make his theories of manifest present value to 
the farmer. His style has the simplicity and directness only 
acquired by those accustomed to speak to practical men. He 
announces at once his object, — the advantages to be gained ; 
and then tells us in the plainest language how to attain it. 

More advancement has been made in Agricultural Chemistry 
in the last ten years, than in any other branch of Science, and 
no mind is better qualified than Mr. Johnston's, to seize upon 



INTRODTJCTIOlSr. 



The scientific principles iipon which the art of culture depends, 
have not hitherto been sufficiently understood or appreciated 
by practical men. Into the causes of this I shall not here in- 
quire. I may remark, however, that if Agriculture is ever to 
be Ijrought to that comparative state of perfection to which 
many other arts have already attained, it will only be by avail- 
ing itself, as they have done, of the many aids which science 
offers to it. And if the practical man is ever to realise upon 
his farm all the advantages which science is capable of placing 
within his reach, he must become so far acquainted with the 
connection that exists between the art by which he lives and 
the sciences, especially of Chemistry, Greology, and Chemical 
Pliysiology, as to be prepared to listen with candor to the 
suggestions they are ready to make to him, and to attach their 
proper value to the explanations of his various processes which 
they are capable of affording. 

The following little Treatise is intended to present a familiar 
outline of the subjects treated of more at large in my published 



Vin INTRODUCTION. 

Lectures on Agricultural Chemistry and Geology. What, 
in tliis work, has necessarily been taken for granted, or briefly 
noticed, is in the Lectures, examined, discussed, or more fully 
detailed. 

Those who wish to put into the hands of the young a still 
more condensed view of the principles of scientific agriculture, 
will find it in my Catechism of Agricultural Chemistry and 
Geology. To most persons, indeed, it will prove advantageous 
to read the Catechism first, and to pi'oceed from it to the Ele- 
ments, and then to the Lectures. 

Durham, November 1852. 



PREFACE. V 

every new theory mid fact, and to coniljinc tiiem all into a har- 
monious whole. 

The present volume pretends.. to no great recent discoveries 
in Agriculture, but it is believed that in no other work have 
the results of experience and theories been more carefully com- 
pared. 

The writer, in addition to a complete treatise upon the 
Elements of Agricultural Chemistry, suggests modes of thought 
calculated to lead the reader constantly to reflection. What 
each crop and each rotation of crops takes fp^m the soil, is 
carefully shown, that so the farmer may be led to inciuire how 
he can return the elements thus exhausted. Exact analyses are 
given of the various substances used as manure, thus giving aid 
to answer such inquiries. The structure of the various parts of 
plants, the stem, root, and leaves, and their various functions, 
are also carefully considered, with a view of ascertaining both 
how their grow^th may be promoted, and to what useful pur- 
poses they may be applied as manure, when their other uses are 
exhausted. 

The structure of the earth, of its various rock formations, 
which are the foundation of all soils, is lucidly discussed, giving 
an insight into the value of geology as a practical helper in 
husbandry — ^giving us'at the same time direct instruction in the 
best mechanical treatment of the farm, in plowing, subsoiling, 
liud thorough draining. 

The reader will find practical advantage in the suggestions of 
the author as to aduUerations of the various fertilizers now ex- 
tensively used in this country, especially of guano. It is believed 
that gross impositions are already practiced upon the agricultu- 
ral community, in the sale of various articles of little value. It 
is only by the aid of scieutitic men, like our author, that these 



VI PREFACE. 

frauds can be detected, and the community be jirotected from 
imposition, while they reap the full advantage to be derived 
from the use of those articles when honestly supplied to them 
in a pure form. The work is offered to the public, not to su- 
persede the truly-scientific and more technical treatise of Stock- 
hardt in the schools and colleges, not indeed to take the place 
of any existing work, even in our libraries, ])ut as containing the 
matured results of a carefully-trained mind, which has long 
compared the practical notions of the farmer with the theoreti- 
cal ideas of the chemist and geologist, and so wrouglit out a 
fund of valuable knowledge ioY ]p radical men, such as, it is be- 
lieved, no other book supplies. 

Another feature of great value to the work is that it has a 
thoroughly-digested analytical and alphabetical index, so that 
the editor, or student, in discussing any particular subject here- 
in treated, may turn directly to it ; or the farmer, when in doubt 
as to the treatment or composition of certain soils, the compost- 
ing or application of manures, or the fertilizing properties of the 
rocks upon his farm, by the -aid of the index is directly referred 
to the sul)ject in question, where he will usually find such plain 
and practical suggestions as will enable him to derive important 
aid in his operations. 

Simon Brown. 
Boston, 185o. 



ELEMENTS 

OP 

AGEICULTUEAL CHEMISTRY 

ETC. 



CHAPTER I. 



Object of the farmer. — What chemistry, geology, and chemical physiology 
may do for agriculture. — Distinctiou between organic and inorganic sub- 
stances. — The ash of plants and animals. — Simple and compomid bo- 
dies. — What elementary bodies are contained in the organic part of 
soils, plants, and animals. — Properties of carbon, sulphur, phosphorus, 
hydrogen, oxygen, and nitrogen. — Relative proportions of these elemen- 
tary bodies contained in plants and animals. — Meaning of chemical com- 
bination and chemical decomposition. 

The object of the practical farmer is to raise from a given 
extent of land the largest qaantitj of the most valuable pro- 
duce at the least cost, in the shortest period of time, and with 
the least permanent injury to the soil. Chemistry, Geology, 
and Chemical Physiology throw light on every step he takes, 
or ought to take, in order to effect this main object. 

SECTION I. WHAT CHEMISTRY, GEOLOGY, AND CHEMICAL PHYSIO- 
LOGY MAY HOPE TO DO FOR AGRICULTURE. 

But there are certain definite objects which, in their connec- 
tion with agriculture, these sciences hope to attain. Thus, 
without distinguishing the special province of each, they pro- 
pose generally : — 

1 



Z WHAT CHEMISTRY AND GEOLOGY 

. 1°. To colled, to investiga/c, and, if possible, to explain- all 
known facts in practical husbandry. — This is their first duty — a 
laborious, difficult, but important one. Many things which are 
received as facts in agriculture, prove to be more or less untrue 
when investigated and tested by experiment. Many ascertained 
facts appear inexplicable to the uninstructed — many even oppo- 
site and contradictory, whieh known principles clear up and 
reconcile — yet there are many more which only prolonged re- 
search can enable us to explain ! 

2°. From observations and experiments made in the field or in 
the laboratory, to deduce principles which may be more or less appli- 
cable in all circumstances. — Such principles will explain useful 
practices, and confirm their propriety. They will also account 
for contradictory results, and will point out the circumstances 
under which this or that practice may most prudently and most 
economically be adopted. 

Armed with the knowledge of sucli principles, the instructed 
farmer will go into his fields as the physician goes to the bed- 
side of his patient, — prepared to understand symptoms and 
appearances he has never before seen, and to adapt his prac- 
tice to circumstances vrhich have never before fallen under his 
observation. 

To deduce principles from collections of facts is attended 
with mucli difficulty in all departments of knowledge. In agri- 
culture it is at present an unusaally difficult task. Observations 
and experiments in the field have hitherto been generally made 
with too little care, or recorded with too little accuracy, to 
justify the scientific man in confidently adopting them as the 
basis of his reasonings. A new race, however, of more careful 
observers, and more accurate experimenters, is now springing 
up. By their aid, the advance of sound agricultural know- 
ledge cannot fail to be greatly promoted. 

3°. To suggest improved, and, perhaps, previously unthought-of 
methods of fertilising the soil. — A true explanation of twenty 
known facts or results, or useful practices, should suggest nearly 



MAY HOrE TO DO FOR AGRICULTURE. 3 

as many more. Thus the explanation of old errors will not 
only guard the practical man from falling into new ones, but 
will suggest direct improvements he would not otherwise have 
thought of. So, also, the true explanation of one useful prac- 
tice will point out other new practices, which may safely and 
with advantage be adopted, 

4°. To analyse soils, mamircs, and vegetable products. — This is 
a most laborious department of the duties which agriculture 
expects chemistry to undertake in her behalf. 

a. Soils. — The kind and amount of benefit to be derived from 
the analyses of soils, are becoming every day more apparent. 
We cannot, indeed, from the results of an analysis, prescribe in 
every case the kind of treatment by which a soil may at once 
be rendered most productive. In many cases, however, certain 
wants of the soil are directly pointed out by analysis ; in many 
others, modes of treatment are suggested, by which a greater 
fertility is likely to be produced, — and, as our knowledge of 
the subject extends, we may hope to obtain, in every case, 
some useful directions for the improvement or more profitable 
culture of the land. 

b. Manures. — Of the manures we employ, too much cannot 
be known. An accurate knowledge of these will guard the 
practical man against an improvident waste of any of those 
natural manures which are produced upon his farm — thus les- 
sening the necessity for forei"gn manures, by introducing a 
greater economy of those he already possesses. It will also 
protect him against the ignorance or knavery of the manure 
manufacturer. The establishment of such manufactories, con- 
ducted by skilful and honorable men, is one of the most impor- 
tant practical results to which the progress of scientific agricul- 
ture is likely to lead. And if it cannot prevent unsorupulous 
adulterators from engaging in this new traflQc, chemistry can at 
least detect and expose their frauds. 

c. Vegetable Products. — In regard, again, to the products of 
the soil, few things are now more necessary than a rigorous 



4 WHAT CHEMISTRY AND GEOLOGY MAY HOPE TO DO, &C. 

analysis of all their parts. If we know what a plant contains, 
we know what elementary bodies it takes from the soil, and, 
consequently, what the soil must contain, if the plant is to grow 
upon it in a healthy manner, — that is, we shall knov,^, to a cer- 
tain extent, how to manure it. 

On the other hand, in applying vegetable substances to the 
feeding of stock, it is of equal importance to know what they 
severally contain, in order that a skilful selection may be made 
of such kinds of food as may best suit the purposes we intend 
them to serve: 

5°. To explain how plants groio and are nourished, and how 
animals are supported and most cheaply fed.- — What food plants 
require, and at different periods of their growth, whence they 
obtain it, how they take it in, and in what forms of chemical 
combination ? Also, what kind and quantity of food the 
animal requires, what purposes different kinds of food serve iu 
the animal economy, and how a given quantity of any variety 
of food may be turned to the best account ? What questions 
ought more to interest the practical farmer than these ? 

Then there are certain peculiarities of soil, both physical and 
chemical, which are best fitted to promote the growth of each 
of our most valuable crops. There are also certain ways of 
cultivating and manuring, and certain kinds of manure which 
are specially favorable to each, and these again vary with every 
important modification of climate. Thus chemical physiology 
has much both to learn and to teach in regard to the raising 
of crops. 

So, different kinds and breeds of domestic animals thrive best 
upon different kinds of food, or require different proportions of 
each, or to have it prepared in different ways, or given at differ- 
ent time«. Among animals of the same species also, the grow- 
ing, the full-grown, the fattening, and the milking animal, re- 
spectively require a peculiar adjustment of food in kind, quan- 
tity, or form. All such adjustments the researches of chemistry 
and physiology alone enable us accurately to make. 



ORGANIC AND INORGANIC PARTS OF PLANTS, &C, 5 

6°. To test the opinions of theoretical men. — Erroneous opinions 
lead to grave errors in practice. Such incorrect opinions are 
not unfrequently entertained and promulgatetl even by eminent 
scientific men. They are in this case most dangerous and most 
difficult to overturn ; so that against these unfounded theories 
the farmer requires protection, no less than against the quack- 
ery of manufactured manures. It is only on a basis of often 
repeated, skilfully conducted, and faithfully recorded experi- 
ments, made by instructed persons, that true theories can ever 
be successfully built up. Hence the importance of experiments in 
practical agriculture. 

Such are the principal objects which chemistry, aided by geo- 
logy and physiology, either promises or hopes to attain. In no 
district, however, will the benefits she is capable of conferring 
upon agriculture be fully realised, unless her aid be really sought 
for, her ability rightly estimated, and her interference earnestly 
requested. In other words, what we already know, as well as 
what we are every day learning, must be adequately diffused 
among the agricultural body, and in every district means must 
be adopted for promoting this diffusion. It is in vain for che- 
mistry and the other sciences to discover or suggest, unless her 
discoveries and suggestions be fully made known to those whose 
benefit they are most likely to promote. 

SECTION II. OF ORGANIC AND INORGANIC MATTER, AND OF THE OR- 
GANIC AND INORGANIC PARTS OF ANIMALS, PLANTS, AND SOILS. 

In the prosecution of his art, two distinct classes of substances 
engage the attention of the practical farmer — the living animals 
and crops he raises, and the dead soils from which the latter 
are gathered. If he examine any fragment of an animal or 
vegetable, either living or dead, — a piece of flesh or wood, for 
example, — he will observe that it exhibits pores of various 
kinds arranged in a certain order ; that it has a species of inter- 
nal structure ; that it has various parts or organs ; in short, 



6 ORGANIC AND INORGANIC PARTS OF PLANTS, &C. 

that it is what physiologists term organised. If he examine, in 
like manner, a lump of earth or rock, he will perceive no such 
structure. To mark this distinction, the parts of animals and 
vegetables, either living or dead — whether entire or in a state 
of decay — are called organic bodies, while earthy and stony sub- 
stances are called inorganic bodies. 

Organic substances are more or less readily burned away and 
dissipated by heat in the open air ; inorganic substances are 
generally fixed and permanent in the fire. 

Now the crops which grow upon the land, as well as the soil 
in which they are rooted, contain a portion of both of these 
classes of substances. In all fertile soils there exists from 3 to 
10 per cent, of vegetable or other matter, of organic origin. If 
we heat a portion of such a soil to redness in the open air, as 
in the annexed, (fig. 1,) this organic matter will burn away, 
leaving the inorganic or mineral matter behind. By this burn- 
ing, most soils are changed in color, but, if previously dried, 

Pig. 1. 




are not materially diminished in bulk. The inorganic matter 
forms by far their largest part. 

All vegetables, again, as they are collected for food, leave, 
when burned, a sensible quantity of inorganic ash ; but of them 
it forms only a small part. Wood leaves about a J per cent, 
grain 2 or 3 per cent, straw about 5 per cent ; and only in 
rare cases does the ash left amount to 15 or 20 per cent of the 
weight of a vegetable substance. Hence, when a handful of 
wheat, wheat straw, hay, &c., is burned in the air, a compara- 
tively small weight of matter only remains behind. Every one 



r 



SIMPLE AND COMPOUND BODIES. T 

m familiar with tliis fact who has seen the small bulk of ash that 
is left when weeds, or thorn-bushes, or trees, are burned in tlie 
field, or when a hay or corn stack is accidentally consumed. 
Yet this ash is ver/ important to the plant, and the study of its 
true nature throws much light, as we shall hereafter see, on the 
practical management of the land on which any given crop is to 
be made to grow. It strikes us also as being important in 
quantity, when we consider how much may be contained in an 
entire crop. Thus the quantity of ash left by a ton of wheat 
straw is sometimes as much as 360 lb., and by a ton of oat straw 
as much as 200 lb, A ton of the grain of wheat leaves on an 
average about 45 lb., of the grain of oats about 9 lb., and of 
oak wood only 4 or 5 lb. 

Animal substances also leave a proportion of ash when burned 
in the air. Dry flesh and hair leave about 5 per cent of their 
weight of inorganic ash ; dry bones more than half their weight. 

Generally, therefore, the soil contains little organic and much 
inorganic or mineral matter — the plant much organic and little 
mineral — the animal, in its soft parts, little, in" its hard or solid 
parts, much mineral matter. 

SECTION III. OF SIMPLE OR ELEMENTARY AND COMPOUND BODIES. 

The various kinds of organic and inorganic matter of which 
soils, plants, and animals consist, are distinguished by chemists 
into two groups. Those which, by the agency of heat, or by 
any chemical or other means, can be separated into two or more 
unlike kinds of matter, are called compound bodies — those which 
cannot be so separated, are called simple or elementary bodies. 

Gold, iron, sulphur, and pure charcoal are simple substances. 
They cannot by any known means be separated or resolved into 
more than one substance. 

Wood, flesh, limestone, sand, &c., are CGmpound substances. 
We are acquainted with methods by which they can each be 
split up into two or more substances different from each other, 



8 PROPERTIES OF CARBON 

and from the wood or flesh, &c., from which they are ob- 
tained. 

Of simple or elementary bodies sixty-four are at present 
known to chemists. All the other forms of matter which occur 
in the animal, vegetable, or mineral kingdoms are compound. 

SECTION IV. OF THE ELEMENTARY SUBSTANCES OF WHICH THE 

ORGANIC PART OF SOILS, PLANTS, AND ANIMALS CONSISTS. 

The organic or combustible part of soils, plants, and animals 
is composed almost exclusively of four elementary substances, 
known to chemists by the names of carbon, hydrogen, oxygen, 
and nitrogen. It usually contains also a minute proportion of 
sulphur and phosphorus. 

Of these, carbon, sulphur, and phosphorus are solid substances ; 
while hydrogen, oxygen, and nitrogen are gases, or peculiar 
kinds of air. Their properties are as follows : — 

1. Carbon. — When wood is burned in a covered heap, as is 
done by the charcoal burners, — or is distilled in iron retorts, as 
in making wood-vinegar, — ^it is charred, and is converted into 
common wood charcoal. This charcoal is the most usual and 
best known variety of carbon. It is black, soils the fingers, and 
is more or less porous, according to the kind of wood from which 
it has been formed. Coke obtained by charring or distilling 
coal is another variety. It is generally denser or heavier than 
charcoal, though usually less pure. Black lead is a third va- 
riety, still heavier and more impure. The diamond is the only 
form in which carbon occurs in nature in a state of perfect 
purity. 

This latter fact, that the diamond is pure carl3on — that it is 
essentially the same substance* with the finest and purest lamp- 
black — is very remarkable ; but it is only one of the numerous 
striking circumstances that every now and then present them- 
selves before the inquiring chemist. 

Charcoal, the diamond, lamp-black, and all the other foriiis 



PROPERTIES OF HYDROGEN. 



9 



of carbon, burn away more or less slowly wlien heated to red- 
ness in the ah* or in oxygen gas, and are converted into a kind 
of gas known by the name of carhonic acid gas. The impm^e 
varieties, when burned, leave behind them a greater or less pro- 
portion of ash. 

2. Sulphur is a well known solid substance of a light yellow 
color, and faint peculiar odor. It burns with a pale-blue 
flame, and in burning gives off fumes possessed of a strong pun- 
gent characteristic smell. 

3. Phosphorus is a yellowish waxy substance of a peculiar 
smell, which smokes in the air, shines in the dark, takes fire by 
mere rubbing, and burns with a large bright flume and much 
white smoke. Like sulphur, it exists in all plants and animals, 
though in comparatively small quantity. Like sulphur, also, it 
is employed largely in the arts, especially in the manufacture of 
lucifer matches. 

4. Hydrogen. — If oil of vitriol (sulphuric acid) be mixed 

Eig. 2. 




with twice its bulk of water, and be then poured upon iron 
filings, or upon small pieces of zinc, the mixture will speedily 
begin to boil up, and bubbles of gas will rise to the surface of 
the liquid in great abundance. These are bubbles of hydrogen gas. 
1* 



; 
( 

10 PROPERTIES OF OXYGEN. 

If the experiment be performed in a bottle, the hydrogen 
which is produced will gradually drive out the atmospheric air 
it contained, and will itself take its place. If a taper be tied 
to the end of a wire, and, when lighted, be introduced into the 
bottle, (fig. 2,) it will be instantly extinguished ; while the 
hydrogen will take fire, and burn at the mouth of the bottle 
with a pale yellow flame. If the taper be inserted before the 
common air is all expelled, the mixture of hydrogen and com- 
mon air will burn with an explosion more or less violent, and 
may even shatter the bottle and produce serious accidents. 
This experiment, therefore, ought to be made with caution. It 
may be more safely performed in a common tumbler, (fig. 3,) 

Fiff. 3. 




covered closely by a plate, till a sufficient quantity of hydrogen 
is collected, when, on the introduction of the taper, the light 
will be extinguished, and the hydrogen will burn with a less 
violent explosion. Or the gas may be prepared in a retort, and 
collected over water, as shown in fig. 4. 

This gas is the lightest of all known substances, rising through 
common air as wood does through water. Hence, when con- 
fined in a bag made of silk, or other light tissue, it is capable 
of sustaining heavy substances in the air, and even of carrying 
them up to great heights. For this reason it is employed for 
filling and elevating balloons. 

Hydrogen gas is not known to occur any where in nature in 
any sensible quantity in a free state. It is very abundant in 
water, and in many other substances, in what by chemists is 
called a state of combination. (See pages 15 and 24.) 

5. Oxygen. — When strong oil of vitriol is poured upon black 



PROPERTIES OF OXYGEN, 



11 



oxide of manganese, and heated in a glass retort, (fig. 4,) or 
when a mixture of chlorate of potash with an equal weight of 



Fio-. 4. 




oxide of manganese, or when chlorate of potash alone, or red 
oxide of mercury alone, is so heated — or when saltpetre, or the 
black oxide of manganese, is heated alone in an iron bottle, — 
in all these cases a kind of air is given off, to which the name 
of oxygen gas is given. It is obtained with the greatest ease, 
rapidity, and purity, from the mixture of chlorate of potash and 
oxide of manganes^e. 

A very elegant method of preparing the gas is to put a few 

Fig. 5. 




grains of rtd oxide of mercury into a tube, and apply the heat of 
a lamp as in fig. 5. Oxygen gas will be given off' while minute 
globules of metallic mercury will condense on the cool part of 
the tube. The presence of oxygen in the tube is shown by in- 



12 PREPARATION OF NITROGEN. 

troducing iiito one end of it a half-kindled match, when it will 
be seen to burn up brilliantly. 

It is the characteristic property of this gas, that a taper, 
when introduced into it, burns with great rapidity, and with ex- 
ceeding brilliancy, and continues to burn till cither the whole of 
the gas disappears or the taper is entirely consumed. In this 
respect it differs both from hydrogen and from common air. If 
a living animal is introduced into this gas, its circulation and 
its breathing become quicker — it is speedily thrown into a fever 
■ — it lives as fast as the taper burned^and, after a few hours, 
dies from excitement and exhaustion. This gas is not lighter, 
as hydrogen is, but is about one-ninth part heavier than com- 
mon air. 

In the atmosphere, oxygen exists in the state of gas. It 
forms about one-fifth of the bulk of the air we breathe, and i« 
the substance which, in the air, supports all animal life, and the 
combustion of all burning bodies. It is necessary also to the 
growth of plants, so that were it by any cause suddenly re- 
moved from the atmosphere of our globe, every living thing would 
perish, and all combustion would become impossible. 

6. N'lTROGEN. — This gas is very easily prepared. Dissolve a 
little green copperas in water, and pour the solution into a flask, 
or crystal bottle, provided with a good cork. Add a little of 
the hartshorn of the shops (liquid ammonia) till it is quite muddy, 
put in the cork tight, and shake the bottle well for five minutes. 
Loosen the cork well without removing it, so as to allow air to 
enter the bottle. Cork tight again and shake as before. Re- 
peat this as often as the loosening of the cork appears to admit 
any air, and after finally shaking it, allow it to stand for a few 
minutes. The air now in the bottle is nearly pure nitrogen gas. 

If a lighted taper be introduced into the bottle it will be 
extinguished by this gas, but no other effect will follow. The 
gas itself does not take fire as hydrogen does. Or if a living 
animal be introduced into it, breathing will instantly cease, and 
it will drop without signs of life. 



COMPOSITION OF THE ORGANIC PART OF PLANTS. 13 

This gas possesses no other remarkable property. It is a 
very little lighter than common air, (as 9^1 to 100,) and exists 
in large quantity in an uncombined state in the atmosphere 
only. Of the air we breathe it forms nearly four-fifths of the 
entire bulk— the remainder behig oxygen. In the process 
above described for preparing the gas, the oxygen is absorbed 
by the iron, and the nitrogen left behind. 

These three gases are incapable of being distinguished from 
common air, or from each other by the ordinary senses ; but by 
the aid of the taper they are readily recognised. Hydrogen 
extinguishes the taper, but itself takes fire ; nitrogen simply 
extinguishes it ; while in oxygen the taper burns rapidly and 
with extraordinary brilliancy. 

SECTION V. PROPORTIONS OF THESE ELEMENTARY SUBSTANCES 

CONTAINED IN THE ORGANIC PART OF PLANTS AND ANIMALS. 

Of the one solid substance, carljon, and the three gases, hy- 
drogen, oxygen, and nitrogen, above described, the organic 
part of all vegetable and animal l)odies is essentially" made up. 
In fhose organic sul)stances which contain nitrogen, sulphur 
and phosphorus also are present, but generally in minute pro- 
portion. 

But the organic part of plants contains these four substan- 
ces in very different proportions. Tims, of all the vegetable 
productions which are gathered as feod by man or beast, in 
their dry state, the 

Carbon forms nearly one-half by weight, 
Oxygen rather more than one-third, 
Hydrogen little more than 5 fer cent, 
Nitrogen from \ to 4 ■per cent, 
Sulphur 1 to 5 per cent, 
Phosphorus about a thousandth part. 

This is shown in part by the folloAving table, which exhibits 



14 COMPOSITION OF THE ORGANIC PART OF PLANTS. 

the actual composition of 1000 lb. of some yarieties of the more 
common crops, wlien made ])erfe.ctly dry : — 



Carlson. 


Hydrogen. 


Oxygen. 


Nitroffon. 


Ash. 


Hay, . 458 lb, 


50 lb. 


387 lb. 


15 lb. 


90 1b. 


Red Cloyer Hay, 474 


50 


378 


21 


77 


Potatoes, . 440 


58 


447 


15 


40 


Wheat, . 461 


58 


434 


23 


24 


Wheat Straw 484 


53 


389J 


H 


70 


Oats, . 507 


64 


367 


22 


40 



Oat Straw, 501 54 390 4 51 

It is to be obseryed, lioweyer, that in drying by a gentle 
heat, 1000 lb. of common hay from the stack lost 158 lb. of 
water; of clover hay, 210 lb.; of potatoes wiped dry externally, 
159 lb. f of wheat, 145 lb. ; of wheat straw, 260 lb. ; of oats, 
151 lb. ; and of oat straw, 28 1 lb. The aboye table represents 
their composition when thus made perfectly dry. 

The bodies of animals contain also a large proportion of 
water ; but the dry matter of their bodies, as a whole, is dis- 
tinguished from that of plants, by containing a larger proportion 
of nitrogen, sulphur, and phosphorus. Some parts of the 
bodies of animals are particularly rich in these ingredients. 
Thus— • 

Dry lean muscle contains 12 to 14 per cent of nitrogen, 
Dry hair or wool about 5 per cent of sulphur ; and 
Dry hone about 6 per cent of phosphorus. 
But in animals, as in plants, the chief constituents are carbon 
and oxygen. Thus, lean beef, blood, white of &^g, and the 
curd of milk, when- quite dry, consist in 100 parts of about — 

Per cent. 
Carbon, . . . . . 55 

Hydrogen, ..... t 

Nitrogen, . . . . . 16 

Oxogen, with a little sulphur and phosphorus, 22 

100 

* Potatoes contain about foiir-fifrhs of their weight of water, or five tons 
of roots contain nearly four tons of water. Turnips contain sometimes up- 
wards of nine-tentlis of their weight of water. 



CHEMICAL COMBINATION AND DEGOMrOSITION. 15 



SECTION VI. OF CHEMICAL COMBINATION AND CHEMICAL DECOM- 
POSITION. 

1°. If the three kmcls of air above spoken of be mixed to- 
gether in a bottle, no change will take place ; and if charcoal 
in fine powder be added to them, still no new substance will be 
produced. Or if we take the ash left by a known weight of hay 
or of wheat straw, and mix it with the proper quantities of the 
four elementary substances — carbon, hydrogen, oxygen, and 
nitrogen — as shown in the above table, we shall be unable by 
this means to form either hay or wheat straw. The elements 
of which vegetable substances consist, therefore, are not merely 
mixed together, they are united in some closer and more inti- 
mate manner. To this more intimate state of union the term 
chemical comhinaticn is applied — the elements are said to be 
chemically combined. 

Thus, when charcoal is burned in the air, it slowly disappears, 
and forms, as already stated, (p. 9,) a kind of air known by 
the name of carbonic acid gas, which rises into the atmosphere 
and diffuses itself through it. Now this carbonic acid is formed 
by the union of the carbon (charcoal) while burning, with the 
oxygen of the atmosphere, and in this new air the two elements, 
carbon and oxygen, are chemically combined. 

Again, if hydrogen be burned in the air by means of a com- 
mon gas jet, (see p. 24,) water is formed, and the hydrogen, 
and a portion of the oxygen of the atmosphere, disappear to- 
gether. The two gases have combined chemically with each other, 
and formed water, 

2°. On the other hand, if a piece of wood, or bit of straw, 
in which the elements are already chemically combined, be 
burned in the air, these elements are separated, and made to 
assume new states of combination, in v/hicli new states they 
escape into the air and become invisible. When a substance is 
thus changed, and converted or separated into other substances 
by the action of heat, or in any other way, it is said to be de- 



16 CHEMICAL COMBINATION AND DECOMPOSITION. 

composed. If it more gradually decay and perish, as animal and 
vegetable substances do, by- exposure to the air and moisture, 
it is said to undergo slow decomposition. 

When, therefore, two or more substances unite together, so 
as to form a third, possessing properties different from both, they 
enter into chemical union — they form a chemical combinatio^f, or 
chemical compound. And when, on the other hand, a compound 
body is so changed as to be converted into two or more sub- 
stances different from itself, it is decomposed. Thus carbon, 
hydrogen, and oxygen undergo a chemical combination in the 
interior of the plant during the formation of wood — while wood, 
again, is decomposed, when in the retort of the vinegar-maker it 
is converted among other substances into charcoal and wood- 
vinegar. So the flour of grain is decomposed when the brewer 
or distiller converts it into ardent spirits ; and so in the experi- 
ment described in section iv, for preparing oxygen gas from red 
oxide of mercury, the oxide is decomposed by the heat, and is 
resolved into its two constituent elements, oxygen and metallic 
mercmy. 



CHAPTER II. 

rorms iu which the organic elements, carbon, hydrogen, oxygen, nitrogen, 
sulphur, and phosjohorus, enter into plants. — Properties of the carbonic, 
humic, ulmic, geic, and crenic acids, and of humine and ulmine. — Of water, 
and its relations to vegetable life. — Of ammonia, its properties and pro- 
duction in nature. — Of other organic alkalies containing nitrogen. — Of 
nitric acid, and its production in the air and in the soil. — Composition of 
the atmosphere. — Of sulphuric 9,nd phosphoric acids. 

SECTION I. FORMS IN WHICH THE ORGANIC ELEMENTS, CARBON, 

HYDROGEN, OXYGEN, NITROGEN, &C.,, ENTER INTO PLANTS. 

It is from their food that plants derive the carbon, hydrogen, 
oxygen, and nitrogen, as well as the sulphur and phosphorus, of 
which their organic part consists. This food enters partly by 
the minute pores of their roots, and partly by those which exist 
in the green parts of the leaf and of the young twig. The roots 
bring up food from the soil, the leaves take it in directly from 
the air. 

Now, as the pores in the roots and leaves are very minute, 
carbon (charcoal) cannot enter them in a solid state ; and as it 
does not dissolve in water, it cannot, in the state of simple car- 
bon, be any part of the food of plants. The same is true of 
sulphur and phosphorus. Again, hydrogen gas neither exists in 
the air nor usually in the soil ; so that, although hydrogen is 
always found in the substance of plants, it does not enter them 
in the state of gas. Oxygen, on the other hand, exists in the 
air, and is directly absorbed both by the leaves and by the roots 
of plants ; while nitrogen, though it forms a large part of the 
atmosphere, is not known to enter directly into plants in any 
considerable quantity. 

The whole of the carbon and hydrogen, therefore, and the 



18 



PROPERTIES OF CARBONIC ACID. 



greater part of the oxygen and nitrogen also, enter into plants 
in a state of chemical combination with other substances. The 
carbon is taken up chiefly in the state of carbonic acid, and of 
certain other soluble compounds which exist in the soil; the 
hydrogen and oxygen in the form of water-; the nitrogen chiefly, 
it is supposed, in those of ammonia, of certain other soluble sub- 
stances containing nitrogen, and of nitric acid ; and the sulphur 
and phosphorus in those of sulphuric and phosphoric acids. It 
will be necessary, therefore, briefly to describe these several 
compounds. 

SECTION II. OF THE CARBONIC, HUMIC, ULMIC, GEIC, AND 

CRENIC ACIDS. 



1. Carbonic Aqid. — If a few pieces of chalk or lime-stone, 
Kg. 6. 




or of common soda, be put into the bottom of a tumbler, and a 
little spirit of salt (muriatic acid) be poured upon them, a boil- 
ing up or effervescence will take place, and a gas will be given off, 
which will gradually collect and fill the tumbler; and when pro- 
duced very rapidly, may even be seen to run over its edges. 



PROPERTIES OF CARBONIC ACID. 19 

This gas is carbonic acid. It cannot be distinguished from 
common air by the eye ; but if a lighted taper be plunged into 
it, the flame will immediately be extinguished, while the gas 

Fiff. T. 




will remain unchanged. This kind of air is so heavy, that it 
may be poured from one vessel into another, and its presence in 
the second vessel recognised as before by the use of the taper. 
Or it may be poured upon a lighted candle, which it will in- 
stantly extinguish, (fig. 6.) This gas has also a peculiar odor, 
and is exceedingly suffocating, so that if a living animal be in- 
troduced into it, life immediately ceases. It is absorbed by 
water — a pint of water absorbing or dissolving a pint of the gas, 
and acquiring a faintly acid taste. 

This gas derives its name of acid from this taste, which it 
imparts to water, and from its property of reddening vegetable 
blue colors, and of combining with alkaline* substances to form 
carbonates. The former property may be shown by passing a 
stream of the gas through a decoction of red cabbage — as in 

* Acids have generally a sour taste like vinegar, and redden vegetable blues. 
Alkalincs, again, have a peculiar taste called alkaline, of which the taste of 
common soda or of hartshorn are examples ; they restore the blue color to 
vegetable blues which have been reddened by an acid, and they unite with 
acids to form chemical combinations, known by the name of salts or sahue 
combinations. 



20 



PROPERTIES OF CARBONIC ACID. 



8 when tlie liquid will gradually become red; the latter, by 

putting lime water into the glass instead of the decoction of red 
cabbage, when the stream of gas will render it milky, forming 

carbonate of lime. 

. Fig. 8. 




Carbonic acid gas exists in the atmosphere ; it is given off 
from the lungs of all living animals while they breathe ; it is 
also produced largely during the burning of wood, of coal, and 
of all other combustible bodies, so that an unceasing supply of 
it is perpetually being poured into the air. Decaying animal 
and vegetable substances also give off this gas, and hence it is 
always present in greater or less abundance in the soil, and es- 
pecially in such soils as are rich in vegetable matter. It is pro- 
duced during the fermentation of malt liquors, or of the ex- 
pressed juices of different fruits, such as the apple, the pear, the 
grape, or the gooseberry — and the briskness of such fermented 
liquors is due to the escape of carbonic acid gas. From fer- 
menting dung and compost heaps it is also given off ; and when 
put into the ground, farm-yard manure imparts much carbonic 
acid to the soil and to the roots of plants. 

Carbonic acid consists of carbon and oxygen only, combined 
together in the proportion of 28 of the former to 12 of the lat- 
ter. Or 100 lb. of carbonic acid contain 28 lb. of carbon and 
1 2 lb. of oxygen. 

It combines with potash, soda, lime, magnssia, ammonia, &c., 
forming carbonates of these bases. 



HUMIC AND ULMIC ACIDS. ' 21 

2. HuMic AND Ulmic Acids. — The soil always contains a 
portion of decaying vegetable matter, (called humus by some 
writers,) and such matter is always added to it when it is ma- 
nured from the farm-yard or the compost heap. During the de- 
cay of this vegetable matter, carbonic acid, as above stated, is 
given off in large quantity, but other substances are also formed 
at the same time. Among these are the two to which the 
names of humic and ulmic acids are respectively given. Both of 
these acids contain much carbon, — they are both capable of en- 
tering the roots of plants, and both, in favorable circumstances, 
help to feed the plant. 

In peat bogs two distinct kinds of turf are frequently recog- 
nised — a light, porous, brown-colored, and a dense, compact, 
black variety. The former abounds in reddish-brown ulmic, the 
latter in brownish-black kmnic 2iC.\di. These acids may readily 
be extracted from the peat by means of potash, soda, or ammo- 
nia, in solutions of which they easily dissolve. 

Thus if the common soda of the shops be dissolved in water, 
and a portion of a rich vegetable soil, or a bit of peat, be put 
into this solution, and the whole then boiled, a brown liquid is 
obtained. If to this brown liquid, spirit of salt (muriatic acid) 
or vinegar be added till it is sour to the taste, a brown fiocky 
tasteless powder falls to the bottom. This brown substance is 
humic or ulmic or geic acid, or a mixture of all the three. In 
our cultivated soils, the humic is more abundant than the ulmic 
acid. 

The quantity of these mixed acids, extracted in this way from 
three rich soils, was respectively 4 J, 5 J, and 8| per cent. In 
most of our arable soils, however, the proportion present is con- 
siderably less. 

3. Geic Acid. — The geic acid resembles the above acids in 
appearance, but contains more oxygen. Like them it exists in 
tlie soil in variable quantity, and may be extracted from it by 
solutions of potash, soda, or ammonia, and is thrown down from 
these solutions by the addition of an acid. 



22 PROPERTIES OF CREXIC AND APOCRENIC ACIDS. 

These three acids have so strong a tendency to coml)ine with 
ammonia, that it is ahnost impossible to ol)tain them free from 
this substance. In the soil they absorb it whenever it is pre- 
sent, and if exposed to the air m a moist state, they drink it in 
from the atmosphere, if any happen to be floating in their neigh- 
borhood. Hence the utility of partially dried peat for absorb- 
ing liquid manure, or for mixing with or covering fermenting 
compost heaps. 

All the three acids above named are sparingly soluble in wa- 
ter, and, therefore, in their uncombined state can afford little 
direct nourishment to plants. They form compounds with lime, 
magnesia, and oxide of iron, which are also very sparingly solu- 
ble, and enter little into the roots of plants. They all dissolve 
readily, however, when they are coml^ined with potash, soda, or 
ammonia. And as the latter substance especially is produced, 
and is always present in the soil, and as these acids attract it 
very strongly, there is good reason for believing that they are 
frequently rendered soluble by it, and that in this way ulmic, 
humic, and geic acids Contribute directly to the nourishment of 
our cultivated crops." 

4. Crenic and Apocrenic Acids. — By these names are dis- 
tinguished two other acid substances which exist in the soil, and 
in a greater degree, perhaps, and more directly, promote the 
growth of plants. They exist in the water of all bogs and mo- 
rasses, and are often met with in considerable quantity in the 
water of springs, especially in such as form an ochrey deposit 
when exposed to the air. They are produced from the humic 
and ulmic acids by the absorption of more oxygen from the at- 
mosphere, and, like them, eagerly combine with ammonia ; but 
they are lighter in color, and much more soluble in water. 

AVhen rich soil is boiled in carbonate of soda, as above de- 
scril)ed, and the humic, ulmic, and geic acids are thrown down 
by the addition of muriatic acid, the crenic and apocrenic acids 
remain still in the solution, and may be separated by further 
processes which it is unnecessary here to describe. 



GENERAL OBSERVATIONS. 23 

All the al;ove acids, and especially the two latter, exist in 
greater or less quantity in the rich brown liquor of the farm- 
yard, whicli is so often allowed to run to waste. They are pro- 
duced, also, during the decay of the mixed animal and vegeta- 
ble manure we add to the soil, and yield to the plant a portion 
of that Supply of organic food Avhich it must necessarily receive 
from the soil. 

5. HuMiNE AND TJlmine arc the names given to certain inso- 
luble black substances formed in the soil along with the humic 
and other acids during the decay of vegetable matter. One of 
the ways in which lime acts beneficially upon the soil is supposed 
to be by disposmg these insoluble matters to enter into new 
states of combination, in which they may become solul)le, and 
thus capable of entering into the roots of plants.* 

Of the important substances above described, I may further 
remark — 

a. That the ulmic acid is the first formed from the decay of 
vegetable matter. Hence, in peat bogs the red turf is usually 
found nearest to the surface. 

b. That the humid acid is formed from the ulmic by the ab- 
sorption of more oxygen from the atmospliere. It consists of 
carbon and water only. (See page 50.) 

c. That the gcic contains more oxygen than the humic acid, 
and is formed from it by the absorption of a further quantity of 
oxygen from the air, or from the water with which it is in con- 
tact. 

d. That the crenic and apocrenic acids contain still more oxy- 
gen, and, along with other substances produced in the soil, are 
formed by the union of the geic acid with another proportion of 
oxygen. 

Thus decaying vegetable matter appears first to form the ul- 
mic, next the humic, than the geic, after that the crenic and 
apocrenic acids. We do not know how many other compounds 

* See in the Chapter " On the Use of Lime, " the sections which treat of 
the chemical action of Umo when appHcd to the soil. 



24 



COMPOSITION OF "WATER. 



may succeed to these by the union of their elements with more 
and more oxygen, before they are entirely resolved into car- 
bonic acid, — the final state to which all these changes ultimately 
lead. 

These excessive absorptions of oxygen by the decaying veg- 
etable matter, promote the production of ammonia in the soil, 
as well as of nitric acid. This fact will be more clearly ex- 
plained in section vi. 

SECTION III. OF WATER, ITS COMPOSITION, AND ITS RELATIONS 

TO VEGETABLE LIFE. 

If hydrogen be prepared in a bottle in the way already de- 
scribed, (p. 9,) and a gas-burner be fixed into its mouth, the 

Fig. 9. 




hydrogen may be lighted, and will burn as it escapes into the 
air, (fig. 9.) Held over this flame, a cold tumbler will become 
covered with dew, or with little drops of water. This water is 
produced during the burning of the hydrogen ; and as its pro- 
duction takes place in pure oxygen gas as well as in the open 



SOLVENT POWER OF WATER. 25 

air, which contains oxygen — a portion of the oxygen and hydro- 
gen alone disappearing — the water formed must contain the 
hydrogen and oxygen which disappear, or must consist of hydro- 
gen and oxygen only. 

This is a very interesting fact ; and were it not that chemists 
are now familiar with many such, it could not fail to appear 
truly wonderful that the two gases, oxygen and hydrogen, by 
uniting together,' should form water — a substance so very dif- 
ferent in its properties from either. Water consists of 1 of 
hydrogen united to 8 of oxygen by weight ; or every 9 lb. of 
water contain 8 lb. of oxygen and 1 lb. of hydrogen. 

Water is so familiar a substance that it is unnecessary to 
dwell upon its properties. When pure, it has neither color, 
taste, nor smell. At 32'^ of Fahrenheit's scale, (the freezing 
point,) it solidifies into ice ; and at 212® it boils, and is con- 
verted into steam. It possesses two other properties, which are 
especially interesting in connection with the growth of plants. 

\st. If sugar or salt be put into water, they disappear, or are 
dissolved. Water has the power of thus dissolving numerous 
other substances in greater or less quantity. Hence, when the 
rain falls and sinks into the soil, it dissolves a portion of the 
soluble substances it meets with in its way, both through the 
air and through the soil, and rarely reaches the roots of plants 
in a pure state. So waters that rise up in springs are rarely 
pure. They always contain earthy and saline substances in 
solution, and these they carry with them when they are sucked 
in by the roots of plants. 

It has been above stated, that water absorbs (dissolves) its 
own bulk of carbonic acid ; it dissolves also smaller quantities 
of the oxygen and nitrogen of the atmosphere ; and hence, 
when it meets any of these gases in the soil, it becomes im- 
pregnated with them, and conveys them into the plant, there to 
serve as a portion as its food. 

In nature, water never occurs in a pure state. It generally 
contains both gaseous ^nd saline substances in a state of solu- 



26 PROPERTIES OF AMMONIA. 

tion ; and this, no doulDt, is a wise provision by which the food 
of phints is constantly renewed and brought within their reach. 

2<r7. Water, as we have shown above, is composed of oxj^gen 
and hydrogen, and by certain chemical processes it can readily 
be resolved or decomposed artificially into these two gases. The 
same thing takes place naturally in the interior of the living 
plant. The roots and leaves absorb the water ; bnt if in any part 
of the- plant hydrogen be required for the formation of the sub- 
stance which it is the function of that part to produce, a portion 
of the water of the sap is decomposed either directly or indi- 
rectly, and its hydrogen worked up, while its oxygen is set free, 
or converted to some other use. So, also, where oxygen is 
required, and cannot be obtained from some more ready source, 
water is decomposed, the oxygen made use of, and the hydrogen 
liberated. Water, therefore, which abounds in the vessels of 
all growing plants, if not directly converted into the substance 
of the plant, is yet a ready and ample source from which a sup- 
ply of either of the elements of which it consists may at any 
time be obtained. 

It is a beautiful adaptation of the properties of this all-perva- 
ding compound — water — that its elements should be so fixedly 
bound together as rarely to separate in external nature, and yet 
to be thus at the command and easy disposal of the vital pow- 
ers of the humblest order of living plants. 

SECTION IV. OF AmiONIA, ITS PROPERTIES AND PRODUCTION IN 

NATURE. 

If the sal-ammoniac, or the sulphate of ammonia of the shops, 
be mixed with quick-lime, a powerful odor is immediately per- 
ceived, and an invisible gas is given off, which strongly affects 
the eyes. This gas is ammonia. Yf ater dissolves or absorbs 
it in very large quantity, and this solution of the gas in water 
forms the common hartsltorn of the shops. The white "solid 



NATURAL mODUCTION OF AMMONIA. 2*1 

smelling-salts of the shops (carbonate of ammonia) are a com- 
pound of ammonia with carbonic acid and a little water. 

Ammonia consists of nitrogen and hydrogen only, in the pro- 
portion of 14 of the former to 3 of the latter by weight ; or It 
lb. of ammonia contain 14 lb. of nitrogen and 3 lb. of hydrogen. 

The decay of animal substances is an important natural 
source of this compound. During tlie putrefaction of dead ani- 
mal bodies, ammonia is invariably given off. From the animal 
substances of the farm-yard it is evolved during their decay or 
putrefaction, as well as from all solid and liquid manures of ani- 
mal origin. 

Ammonia is naturally formed, also, during the decay of veg- 
etable substances in the soil. This happens in one or other of 
three ways. 

a. As in animal bodies, by the direct union of the nitrogen 
with a portion of the hydrogen of which they consist. 

h. Or by the combination of a portion of the hydrogen of the 
decaying plants with the nitrogen of the air. 

c. Or when they decompose in contact, at the same time, 
with both air and water — by their taking the oxygen of a 
quantity of the water, and disposing its hydrogen at the mo- 
ment of liberation, to combine with the nitrogen of the air, and 
form ammonia. 

The production of ammonia by either of the two latter 
modes, takes place most abundantly when the oxygen of the air 
does not gain very ready access. Such are open subsoils in 
which vegetable matter abounds. And thus one of the benefits 
which follow from thorough draining and subsoil ploughing is, 
that the roots penetrate and fill the subsoil with vegetable mat- 
ter, which, by its decay in the confined atmosphere of the sub- 
soil, gives rise to this production of ammonia. When thus 
formed in the soil, it is at once abi^rbed and retained by the 
humic and ulmic acids already described, renders them soluble, 
and enters with them into the roots of living plants. 

Ammonia is also formed naturally during the chemical 



28 OTHER ORGAN' IC ALKALIES. 

changes that are produced in volcanic countries, through the 
agency of subterranean fires. It escapes often in considerable 
quantities from the hot lavas, and from crevices in the heated 
rocks. 

It is produced artificially by the distillation of animal sub- 
stances, (hoofs, horns, &c.,) and during the burning, coking, 
and distillation of coal. Soot contains much ammonia, while 
thousands of tons of that which is i:)resent in the ammoniacal 
liquors of the gas-works, and which might be beneficially applied 
as a manure, are annually carried down by the rivers, and lost 
in the sea. 

Of the ammonia which is given off during the putrefaction of 
animal and vegetable substances, a variable proportion rises 
into the air, and floats in the atmosphere, till it is either decom- 
posed by natural causes, or is dissolved and washed down by 
the rains. In the latter case it sinks into the ground, and finds 
its way into the roots of plants. In our climate, cultivated 
plants appear to derive a considerable proportion of their nitro- 
gen from ammonia. It is one of the most valuable fertilizing 
substances contained in farm-yard manure ; and as it is usually 
present in greater proportion in the liquid than in the solid con- 
tents of the farm-yard, nmch real wealth is lost, and the means 
of raising increased crops thrown away, in the quantities of 
liquid manure which are almost everywhere permitted to ran 
to waste. 

SECTION V. OF OTHER ORGANIC ALKALIES, AND THEIR INFLUENCE 

UPON VEGETATION. 

Ammonia has hitherto been considered by chemists as the 
only organic substance of a volatile and alkaline nature, which 
exercised a sensible influence upon vegetation. But a number 
of other organic alkalies, volatile like ammonia, possessed of a 
powerful odor, soluble in water, and like it containing nitrogen^ 
have recently been discovered. Some of these are of such a kind 



NITRIC ACID. S{9 

as to be naturally produced, I believe, during the decay and 
fermentation of animal and vegetable substances ; and if so, 
they cannot fail to affect the growth of plants. 

These alkaline comi)ounds contain carbon in addition to the 
hydrogen and nitrogen of which ammonia consists. Hence if 
they exist, or are formed in the soil, they will be able to minis- 
ter these three elements to the wants of the plant, and in a form 
of combination in which they may be more readily converted 
into those substances of which the parts of the plant are com- 
posed. 

IS'o experiments have yet been made upon the relations which 
these compounds bear to vegetable life, to fertility of soil, or to 
fertilizing manures ; but I insert these brief remarks regarding 
them in this place from the persuasion, that the study of these 
relations will afford the materials for an intricate, perhaps, but 
most interesting and important chapter in future histories of the 
phenomena of vegetation. 

SECTION VI. OF NITRIC ACID, AND ITS PRODUCTION IN THE AIR 

AND IN THE SOIL. 

Nitric acid is a powerfully corrosive liquid, known in the shops 
by the familiar name of aquafortis. It is prepared by pouring 
oil of vitriol (sulphuric acid) upon saltpetre, and distilling the 
mixture. The aquafortis of the shops is a mixture of the pure 
acid with water. 

Pure nitric acid consists of nitrogen and oxygen only, united 
in the proportions of 14 of nitrogen, by weight, to 40 of oxygen. 
It is very remarkable that the union of these two gases, so 
harmless in the air, should produce the burning and corrosive 
compound which this acid is known to be. 

It never reaches the roots or leaves of plants in this free and 
corrosive state! It exists and is produced in many soils, and is 
naturally formed in compost heaps, and in most situations where 
animal or vegetable matter is undergoing decay in contact with 



30 PROPERTIES OF NITRIC ACID. 

the air ; but in these cases it is always found in a state of che- 
mical combination. With potash it forms nitrate of jpotash, 
(saltpetre,) with soda, nitrate of soda, with lime, nitrate of lime, 
with magnesia, nitrate of magnesia, with ammonia, nitrate of 
ammonia, and so on. All these nitrates are very soluble in wa- 
ter, and it is generally in the state of one or other of these com- 
pounds that nitric acid exists in the soil and reaches the roots 
of plants. 

It is well known that saltpetre — called also nitre, or nitrate 
of potash — is in India obtained by washing the rich alluvial soil 
of certain districts with water, and evaporating the clear solu- 
tion to dryness. On the continent of Europe, artificial nitre- 
beds are formed by mixing together earthy matters of various 
kinds with the liquid and dung of , stables, and forming the mix- 
ture into heaps, which are turned over once or twice a year. 
These heaps, on washing, yield an annual crop of impure salt- 
petre. The soil around our dwellings, and upon which our 
towns and villages stand, becomes impregnated with animal mat- 
ter of various kinds through defective drainage, and is thus con- 
verted into extensive nitre-beds, in which nitric acid and nitrates 
are produced in great abundance. The rains that fall and sink 
into the soil wash these downwards into the wells, if any are 
near. Hence nitrates usually abound in wells which are dug 
within the walls of large towns ; and the waters of such wells 
are generally unwholesome to man, though they would wonder- 
fully nourish plants, if employed for the purposes of irrigation.* 

Nitric acid is also naturally formed, and in some countries 

* " In Leon (Nicaragua) the practice of burying in the churches has al- 
ways prevailed, and is perpetuated through the influence of the priests who 
derive a considerable fee from each burial. The consequence is, that the 
ground within and around the churches has become (if tiie term is admissi- 
ble) saturated with the dead. The burials are made, according to the amount 
paid to the Church, for from ten to twenty-five years, at 'the end of which 
time tlw hones ivith the earth jiround them are removed and sold to the manu- 
facturers of nitre." — Squier's Nicaragua, vol. i. p. 384. 



PRODUCTION OF NITRIC ACID. 31 

probably in large quantities, by the passage of electricity through 
the atmosphere. The air consists of oxygen and nitrogen mixed 
together, but when electric sparks are passed tlirough a quan- 
tity of air, minute portions of the two gases uiiiU together che- 
mically, so that every spark which passes forms a small quantity 
of nitric acid. A flash of lightning is only a large electric 
spark ; and lience* every flash that crosses the air produces 
along its patli a Sensible proportion of this acid. Where tlum- 
der-storms are frequent, much nitric acid, and probably some 
ammonia, are produced in this way in the air. They are washed 
down by the rains — in which they have frequently been de- 
tected—and thus reach the soil, where the acid combines with 
potash, soda, lime, &c., and produces the nitrates above men- 
tioned. 

It has long been observed that those parts of India are the 
most fertile in which saltpetre exists in the soil in the greatest 
abundance. The nitrates of soda and potash have been found 
among ourselves, also, wonderfully to promote vegetation, when 
artificially applied to growing crops ; and it is a matter of fre- 
quent remark, that vegetation seems to be refreshed and invigo- 
rated by the fall of a thunder-shower. There is, therefore, no 
reason to doubt that nitric acid is really beneficial to the gene- 
ral vegetation of the globe. And since vegetation is most lux- 
uriant in those parts of the glolie where thunder and lightning* 
are most abundant, it would appear as if tlie natural production 
of this compound body in the air, to be afterwards brought to 
the earth by the rains, were a v^^ise and beneficent contrivance 
by which the health and vigor of universal vegetation is in- 
tended to be promoted. 

It is from nitric acid, thus universally produced and existing, 
that plants appear to derive a large — probably, taking the vege- 
tation of the earth as a whole, the largest — proportion of their 
nitrogen. In all climates, they also derive a portion of this 
element from ammonia, and from other soluble compounds con- 



32 COMPOSITION OF THE ATMOSPHERE. 

taming nitrogen; but less, probably, from these sources in tropi- 
cal than in temperate climates.* 

SECTION Vn. OF THE COMPOSITION OF THE ATMOSPHERE. 

The air we breathe, and from which plants derive a portion of 
their nourishment, consists of a mixture of oxygen and nitrogen 
gases, with a minute quantity of carbonic acid, and a variable 
proportion of watery vapor. Every hundred gallons of dry air 
contain about 21 gallons of oxygen and T9 of nitrogen. The 
carbonic acid amounts only to one gallon in 2500, while the 
watery vapor varies from one to two and a half gallons (of 
steam) in 100 gallons of common air. 

The oxygen of the atmosphere is necessary to the breathing 
of animals, to the life of plants, and to the burning of bodies 
in the air. The nitrogen serves principally to dilute the strength, 
so to speak, of the pure oxygen — in which gas, if unmixed, 
animals would live, and combustibles burn with too great ra- 
pidity. The small proportion of carbonic acid in the atmo- 
sphere affords an important part of their food to plants, and the 
watery vapor aids in keeping the surfaces of animals and plants 
in a moist and pliant state; while, in due season, it descends 
also in refreshing showers, or studs the evening leaf with spark- 
ling dew. 

There is thus in the composition of the atmosphere a beau- 
tiful adjustment to the nature and necessities of living beings. 
The energy of the pure oxygen is tempered, yet not too much 
weakened, by the admixture of nitrogen gas. The carbonic 
acid, which, when undiluted, is noxious, especially to animal life, 
is mixed with the other gases in so minute a proportion, as to 
be harmless to animals, while it is still beneficial to plants ; and 
when the air is overloaded with watery vapor, it is provided 
that it shall descend in rain. 

* For fuller information on this point, see the Author's Lectures on Agri- 
cultural Ohemistry and Geology., 2d edition. 



SULPnURIC AND PHOSPHORIC ACIDS. 33 

But the air contains besides many other substances not essen- 
tial to its composition, but which exercise, nevertheless, an 
important influence both upon animal and vegetable life. We 
have already seen that nitric acid, and probably ammonia, are 
produced in it by the agency of electricity, and are brought 
down by the rains. There are continually rising into it also 
vapors and exhalations of various kinds from the earth's sur- 
face. The sea sends up a portion of its common salt and other 
constituents, and the land the numberless forms of volatile 
matter which arise from decaying animal and vegetable sub- 
stances, from festering marshes, from burning volcanoes, and 
from countless manufactories and chemical operations. As the 
ocean receives all that water can carry into it, so the atmo- 
sphere receives everything that the air can bear up. 

And lest these ever-rising exhalations should contaminate the 
air, and render it unfit for the breathing of animals, the rains, 
as they descend, dissolve, wash out, and bring them back again 
to the soil. Thus they purify at once, the atmosphere through 
which they fall, and bear refreshment to the land, and the 
means of fertility, wherever they come. 

SECTION VIII. OF SULPHURIC AND PHOSPHORIC ACIDS. 

We have stated in a previous section that sulphuric and phos- 
phoric acids are the chief forms in which sulphur and phospho- 
rus respectively enter into plants. 

1°. Sulphuric Acid — known also as oil of vitriol — is a very 
heavy, oily-looking, sour, and corrosive liquid, which becomes 
hot when mixed with water, chars and blackens straw or wood 
when immersed in it, and is capable of dissolving many organic 
and inorganic substances. It is manufactured by burning sul- 
phur in large leaden chambers, and consists of sulphur and 
oxygen only — combined with a little water. One pound of 
sulphur produces about three pounds of tlie strongest sulphuric 
acid. 

2* 



34 SULPHURIC AND PHOSPHORIC ACIDS. 

This acid combines with potash, soda, lime, magnesia, and 
ammonia, and forms sulphates. These sulphates exist in the soil, 
and when dissolved by water are conveyed into the sap of plants, 
and supply the sulphur which is necessary for the formation 
of their growing parts. 

The strong acid is now employed largely for dissolving bones 
and the fossil phosphates of lime, from which the artificial ma- 
nure known as super-phosphate of lime is manufactured. In a 
diluted state it has been employed with advantage as a steep 
for barley, and even as a manure for turnips. 

2°. Phosphoric Acid. — If a piece of pho>sphorus be kindled 
in the air, it burns with a brilliant flame, and gives off dense 
white fumes. These white fumes are phosphoric acid. They 
are produced by the union of the burning phosphorus with the 
oxygen of the atmosphere. A 100 lb. of phosphorus, when 
burned, form 227^ lb. of phosphoric acid. 

Yiq;. 10. ■ 




If the experiment be performed under a glass, as in the 
annexed figure, the white fumes of acid will condense on the 
cool inside of the vessel in the form of a white powder, which 
speedily absorbs moisture from the air, and runs to a liquid. 
This acid is very sour and -corrosive. It combines with potash, 
lime, &c., and forms phosphates, and in these states of combina- 
tion it exists in soils and manures, and enters into plants. The 
bones of animals contain a large proportion of this acid, chiefly 
in combination with lime and magnesia, 

Lucifer matches are tipped with a morsel of phosphorus, 
which, wlien rubbed, takes fire and kindles the sulphur. The 
white smoke given off by such a match, when first kindled, con- 
sists of phosphoric acid. 



CHAPTER III. 

Structure of the stem, root, and leaves of plants. — Functions of the root, 
the leaves, and the stem. — How plants draw their nourishment from the 
soil and the air. — Of the substance of plants, and the structure of the 
seed or grain. — Of cellulose, starch, sugar, gum, mucilage, and pectose, 
or pectic acid. — Of the oil or fat, wax, resin, and turpentine of plants. — Of 
gluten, albumen, and casein. — Germination of seeds and growth of plants. 
— Mutual transformations of starch, sugar, and cellulose. — Production of 
cellular fibre from tlie organic food of plants. — Necessity of nitrogen, or 
substances containing it, to the growth of plants. — Forms in which nitro- 
gen may enter into plants. 

From the compound substances described in the preceding 
chapter, plants derive the greater portion of the carbon, hydro- 
gen, oxygen, and nitrogen, with the sulphur and phosphorus of 
which their organic part consists. The living plant possesses 
the power of absorbing these compound bodies, of decom'posing 
them in the interior of its several vessels, and of re-cojnpounding 
their elements in a different way, so as to produce new sub- 
stances, — the ordinary products of vegetable life. 

Before describing the nature of these new substances, I shall 
briefly consider the general structure of plants, and their mode 
of growth. 

SECTION I. OF THE STRUCTURE OF THE STEM, ROOT, AND LEAVES 

. OF PLANTS. 

A perfect plant consists of three several parts: — a root which 
throws out arms and fibres in all directions into the soil ; a 
trunk which branches into the atmosphere on every side ; and 
leaves which, from the ends of the branches and twigs, spread 
out a more or less extended surface into the surrounding air. 



36 STRUCTURE OF THE STEM AND ROOT OF PLANTS. 

Each of these parts has a i3eculiar structure, and special func- 
tions assigned to it. 

1°. The stem of any of our common trees consists of three 
parts — the pith in the centre, the wood surrounding the pith, 
and the bark which covers the whole. The pith consists of a 
collection of minute cells, supposed to communicate horizontally 
with the external air through the medullary rays and the outer 
bark ; while the wood and inner bark are composed of long 
tubes bound together in a vertical position, so as to be capable 
of carrying liquids up and down between the roots and the 
leaves. When a, piece of wood is sawn across, the ends of 
these tubes may be distinctly seen. The branch is only a pro- 
longation of the stem, and has a similar structure. 

2°. Tlie root, immediately on leaving the trunk or stem, has 
also a similar structure. But as the root tapers away, the pith 
disappears — in some, as in the walnut and horse-chestnut, grad- 
ually — in others immediately. The.bark also thins out, and the 
wood softens, till the white tendrils, of which its extremities arc 
composed, consist only of a colorless spongy mass, full of pores, 
and in which no distinction of parts can be perceived. In this 
spongy mass the vessels or tubes which descend through the 
stem and root lose themselves, and by these tubes the spongy 
extremities in the soil are connected with the leaves in the air. 

3°. The leaf is an expansion of the twig. The fibres, which 
are seen to branch out from the base through the interior of the 
leaf, are prolongations of the vessels of the wood, and are con- 
nected with similar prolongations of the inner bark, which usu- 
ally lie beneath them. The green exterior portion of the leaf is, 
in like manner, a continuation of the outer or cellular tissue of 
the bark, in a very thin and porous form. The pores, or mouths, 
{stomata) contained in the green part, are an essential feature 
in the structure of the leaves, and are very numerous. The 
leaf of the common lilac contains as many as 120,000 of them 
on a square inch of surface. They are generally most numerous 
on the under part of the leaf, but in the case of leaves which 
float upon water, they are chiefly confined to the upper part. 



I'UNCTIONS OF THE ROOT. 3t 

The annexed woodcut shows the appearance of the oval pores 
j9 on the leaf of the garden balsam.' Connected with these 
pores, the green part of the leaf consists of or contains a collec- 




tion of tubes or vessels which stretch along the surface of the 
leaf, and communicate, as we have said, with those of the inner 
bark. 

SECTION II. FUNCTIOXS OF THE ROOT, THE LEAVES, AXD THE 

STEM. COURSE AND MOTION OF THE SAP. 

Each of these principal parts of the plant performs its pecu- 
liar functions. 

1°. Functions of the root. — The root sends out fibres in every 
direction through the soil in search of water and of liquid food, 
which its spongy extremities suck in, and send forward with the 
sap to the upper parts of the tree. It is to aid the roots in 
procuring the food more rapidly that in the art of culture such 
substances are mixed with the soil as experience has shown to 
be favorable to the growth of the plants we wish to raise. 

What chemical changes the food is made to undergo in en- 
tering or passing along the roots is not yet understood. 

2°. Functions of the leaf. — It is not so obvious to the common 
observer that the leaves spread out their broad surfaces into the 
air for the same purpose precisely as that for which the roots 
diffuse their fibres through the soil ; the only difference is, that 
while the roots suck in chiefly liquid, the leaves inhale alinost 



38 FUNCTIONS OF THE LEAF. 

solely gaseous food. In the daytime, whether in the sunshine or 
in the shade, the green leaves are continually absorbing carbonic 
acid from the air, aiid giving off oxygen gas. That is to say, 
tliey are continually appropriating carbon from the air.* When 
night comes, this process is reversed, and they begin to absorb oxygen 
and to give off carbonic acid. But the latter process does not 
go on so rapidly as the former ; so that, on the whole, plants, 
when growing, gain a large portion of carbon from the air. 
The actual quantity, however, varies with the season, with the 
climate, and with the kind of plant. The proportion of its 
carbon, which has been derived from the air, is greatly modified, 
also, by the quality of the soil in which the plant grows, and 
by the comparative abundance of liquid food which happens to 
be within reach of its roots. It has been ascertained, however, 
that in our climate, on an average, not less than from one-third 
to four-fifths of the entire quantity of carbon contained in the 
crops we reap from land of average fertility, is really obtained 
from the air. 

We see then why, in arctic climates, where the sun, once risen, 
never sets again during the entire summer, vegetation should 
almost rush up from the frozen soil ; the green leaf is ever 
gaining from the air and never losing, ever taking in and never- 
giving off carbonic acid, since no darkness ever interrupts or 
suspends its labors. 

How beautiful, too, does the contrivance of the expanded 
leaf appear ! The air contains only one gallon of carbonic acid 
in 2500, and this proportion has been adjusted to the health 
and comfort of animals to whom this gas is hurtful. But to 
catch this minute quantity, the tree hangs out thousands of 
square feet of leaf — in perpetual motion, through an ever-moving 
air ; and thus, by the conjoined lal)ors of millions of pores, the 
substance of whole forests of solid wood is slowly extracted from 
the fleeting winds. I have already mentioned the number of 

* Since carbonic acid, as shown in the previous chapter, (p. 20,) consists 
only of carbon and oxygen. Of these the leaves retain the carbon and re- 
ject the oxygen. 



SUBSTANCE OF PLANTS. 39 

pores which have been observed on a square mch of leaf ; and 
when I add that on a single oak tree seven millions of leaves 
have been counted, the multitude of absorbing mouths in a for- 
est — like those of the coralline animals in a reef — will appear 
equal to the most gigantic eifects. 

The green stem of the young shoot, and the green stalks of 
the grasses, also abound in pores, and consequently absorb car- 
bonic acid, and give off oxygen, as the green leaf does ; and 
thus a larger supply of food is afforded when the growth is most 
rapid, or when the short life of the annual plant demands much 
nourishment within a limited time. The yellow and red leaves 
and parts of plants give off no oxygen, (Senebier.) 

3°. Functions of the stem. — From the spongy part of the root 
the sap ascends through the vessels of the woody stem till it is 
diffused over the interior of the leaf by the woody fibres which 
the leaf contains. During this passage the substances which the . 
sap contains undergo certain chemical changes, which are as yet 
not well understood. From the woody fibre, of the leaf — along 
the vessels which lie beneath these fibres, and are covered by 
the green part of the leaf — and after it has absorbed or given 
off the gases which the pores transmit, the sap is returned 
towards the outer part of the stem, and through the vessels of 
the inner bark descends again to the root. 

4°. ^oiirse and inoticn of the saj). — In the living plant, at least 
till it has passed maturity, most of the vessels are full of sap, 
and this sap is in continual motion upwards within the stem, and 
downwards along its surface within the inner bark. In spring 
and autumn the motion is more rapid. In winter it is some- 
times scarcely, perceptible ; yet the sap, except when frozen, is 
supposed to be rarely quite stationary in any part of the tree. 

SECTION III. OF THE SUBSTANCES OF WHICH PLANTS CHIEFLY 

CONSIST, AND OF THE STRUCTURE OF THEIR SEEDS. 

In the way above described, the perfect plant derives from the 



40 SUBSTANCE OF PLANTS. 

soil and from the air the food by which it is sustained and ena- 
bled to grow. In the substance or stem of plants thus formed, 
and in their seeds, various chemical compounds exist, but they 
may all be included in three main groups or classes. 

When the grain of wheat, barley, oats, rye, Indian corn, &c., 
is sent to the mill to be ground, two products are obtained — the 
bran or husk, and the flour. When washed free from flour, the 
bran or husk is tasteless, insoluble in water, and woody. It is 
the same thing, indeed, for the most part, as the cellular and 
fibrous part of wood or straw. 

Again, when a portion of the flour is made into dough, and 

Fig. 12. 




this dough is kneaded with the hand under a stream of water 
upon a piece of muslin, or on a fine sieve, as long as the water 
passes through milky — there will remain on the sieve a glutinous 
sticky substance resembling bird-lime, while the milky water will 
gradually deposit a pure white powder. This white powder is 
starch, the adhesive substance which remains on the sieve is glu- 
ten. Both of these substances exist, therefore, in the flour ; they 
both also exist in the grain. 

Further, when bruised wheat, oats, Indian corn, linseed, or 
even chopped hay and straw, are boiled in alcohol or ether, a 
portion of oil or fat, of wax and of resin, is extracted, and is ob- 



THE STARCH GROUP. 



41 



tained separately by allowing the solution to evaporate to dry- 
ness in the air. 

Thus, from the seed or grain we have obtained four different 
substances — the woody part which covers it, starch, gluten, and 
fat. The annexed woodcut shows the position and relative 
quantities of the last three substances in the seeds of wheat, bar- 



Indian 



Barley. 




ley, and Indian corn. Thus, a shows the position of the oil in 
the outer part of the seed. It exists in minute drops, enclosed 
in six-sided cells, which consist chiefly of gluten, h the posi- 
tion and comparative quantity of the starch, which in the heart 
of the seed is mixed with only a small proportion of gluten, c 
the germ or chit which contains much gluten. 

These substances represent the three great classes of organic 
bodies of which the bulk of all plants is made up. 

The woody matter and the starch represent what is called the 
starch group. The gluten represents the gluten or albumen 
group. The oil or resin represents the fatty group. 

I shall briefly describe these several groups or classes of sub- 
stances. 

SECTION IV. OF THE STARCH GROUP WOODY FIBRE, STARCH, GUM, 

MUCILAGE, SUGAR, AND PECTOSE, OR PECTIC ACID. 

The starch group comprehends a great number of different 
substances, possessing different properties, but all characterised 
by this similarity in composition, that they consist of carbon and 
water only. 



42 CELLULOSE, STARCHES, GUMS AND MUCILAGES. 

The following are the principal substances belonging to this 
class : — 

1°. Cellulose or woody fibre. — This forms the walls of the cells 
of plants, the fibres of cotton and linen, the woody part of the 
husk or covering of the seed, and a large portion of the sub- 
stance of wood, hay, straw, &c. It is insoluble in water, both 
in the fresh and dry states, but, as it exists in fodder, appears, 
after due mastication, to be in some degree soluble in the stom- 
achs of animals. It consists of 36 parts by weight of carbon, 
and 45 of water. 

2°. The starches. — There are several varieties of starch besides 
that which occurs in the flour of wheat, oats, barley, the pota- 
to, &c. These are all insoluble in cold water, but give a jelly 
with boiling water. The Iceland moss, and some other lichens, 
contain a starch which gives a jelly with boiling water, but 
which is somewhat different from that of common starch ; while 
the roots of the dahlia and the dandelion give a starch which 
dissolves in boiling water, but does not form a jelly, and fails 
again in a powdery state as the solution cools. 

Common starch, and that of the dandelion and the hchen, 
consist, like woody fibre, of 36 parts of carbon by weight, and 
45 of water; that of the dahlia contains a very little more 
water. 

3°. The gums. — When common starch is heated in an oven 
to 300° F., or when it is mixed with water containing a little 
sulphuric acid and gently heated, it is changed into a soluble 
gummy adhesive substance, to which the name of dextrin is 
given. In this soluble state, starch is supposed to exist abun- 
dantly in the sap of plants. The name arabine is given to 
gum arable, which is soluble in cold water, and ceracine to 
cherry tree gum, which is insoluble in cold, but dissolves i;^adily 
in boiling water. All these three varieties of gum consist, like 
common starch and woody fibre, of 36 parts by weight of car- 
bon, united to 45 parts of water. 

4°. The mucilages. — The name of mucilage is given to gum 



CANE AND GRAPE SUGARS. 43 

tragacanth, wliicli does not dissolve, but swells out into a jelly 
when placed in water — to the adhesive matter which v/ater ex- 
tracts from linseed and other oily seeds, and to the jelly which 
is obtained from the roots of the orchis, (Salop,) the mallow, 
&c. It consists of 48 parts by weight of carbon, and 51 of 
water. 

5°. The, sugars. — In the sap of plants several kinds of sugar 
occur; but those called cane and grape sugars are the most 
abundant. 

Cane sugar exists in the sugar cane, the maple, tlie beet, the 
stalks of corn, and in many other plants. In the ordinary states 
of loaf sugar, crystallised sugar, sugar-candy, &c., it consists of 
48 parts of carbon by weight, and 66 of water. 

Grape sugar exists naturally in the grape, in fruits in general, 
and in honey. It is formed artificially when cellulose or starch 
is boiled for a length of time in water made slightly sour by 
means of sulphuric acid, (oil of vitriol.) It is less sweet than 
cane sugar, and in its crystallised state consists of 48 of carbon 
by weight, and 84 of water. 

The following table exhibits the relative composition of these 
several substances in a hundred parts, as nearly as it can be 
expressed in whole numbers : — • 





Carbon. 


Water. 


Cellulose or woody fibre, 


44 


56 


Starch, .... 


44 


56 


Gum, ..... 


44 


56 


Mucilage, .... 


46 


54 


Sugar of the cane, 


42 


58 


Sugar of the grape, . » 


36 


64 



In stating that these substances consist of carbon and water 
only, I have adopted, for the sake of clearness and simplicity, a 
mode of expression which has not yet been shown to be quite 
correct. It is not certain that these substances contain water 
in the proportions above stated, but they contain hydrogen and 
oxygen in the proportions (1 to 8) in which they form water. 
For simplicity, therefore, we may suppose these two elementary 



44 FATTY SUBSTANCES OF PLANTS. 

bodies actually to exist in the vegetable substances above de- 
scribed in the form of water. 

6°. Pedose and jpedic acid. — The reader will not fail to be 
struck with the remarkable circumstance, that substances so 
different as woody fibre, starch, and gum, should yet consist of 
the same elements — charcoal and water united together in the 
same proportions. In some vegetable substances, however, 
which otherwise resemble starch and gum, and may be classed 
along with them, the hydrogen and oxygen do not exist exactly 
in this proportion. In fleshy fruits, such as the plum, peach, 
apricot, apple, pear, &c., and in the bulbs or roots of the turnip, 
the carrot, the parsnip, &c., there exists no starch, but in its 
stead a substance to which the name of pectose and sometimes 
of fedic acid is given. This substance is nearly as nutricious as 
search, and serves the same purposes when eaten. It contains, 
however, less hydrogen and more oxygen than starch does, and 
changes also more readily into other substances both in the 
plant and in the stomach. 

SECTION V. OF THE FATTY SUBSTANCES OF PLANTS. 

The fatty substances which occur in plants are of three kinds 
— the true fats and oils, the waxes, and the turpentines and 
resins. They all agree in containing less oxygen than would be 
required to convert their hydrogen into water — less than 8 to 1 
by weight. 

1°. The true fats which have as yet been found in plants are 
divided into two classes — the soUd and the liquid fats. ' 

a. Solid fats. — When almond, olive, or linseed oil is exposed 
to a very low temperature, a portion of it freezes or becomes 
solid. This portion may be separated, and by pressure may be, 
in great measure, freed from the liquid portion. 

The solid part thus obtained from most vegetable oils is called 
margarine, and is identical with the solid part of butter, and of 
the fat of man, of the horse, and of some other animals. Some 



SUBSTANCES CONTAINING NITROGEN. 45 

plants yield a solid fat called steariiie, which is the same thing 
as the solid fat of the cow, the sheep, the pig, the goat, and 
many other animals. 

h. To the liquid fats the name of elaine is given. That 
obtained from the oils of almonds, olives, &c., which are called 
fat oils, is somewhat different from that of which linseed, wal- 
nut, and other drying oils chiefly consist. The liquid oil ex- 
pressed from the fat of animals consists chiefly of the former 
variety of elaine. 

2°. The waxes. — Many plants produce wax. It coats the 
flowers and leaves of many trees and shrubs, and forms the 
beautiful bloom which covers the grape and other fruits. From 
these the bees collect it; and though the different varie- 
ties of wax differ somewhat in properties, they all agree with 
bees-wax in being insoluble in water, partially soluble in alcohol, 
nearly without taste and very combustible. 

3°. The turpentines and resins abound in trees of the pine 
tribe. They are all insoluble in water, but readily soluble in 
alcohol; are more combustible than either true fat or wax, and 
contain less oxygen than either. 

Nothing resembling either wax or resin is found in the bodies 
of animals. 



SECTION VI. OF VEGETABLE SUBSTANCES CONTAINING NITROGEN 

THE GLUTEN OR ALBUMEN GROUP. 

In washing the dough of wheaten flour, we have seen (p. 
40) that a portion remains on the sieve or muslin, to which the 
name of gluten is given. This substance contains nitrogen in 
addition to the carbon, hydrogen, and oxygen which are present 
in the bodies described in the preceding sections, and is the re- 
presentative of an entire class of important substances into 
Avhich nitrogen enters as a constituent. I shall briefly mention 
the most important of these substances. 

1°. Gluten. — This is obtained from the dough of wheaten 



46 ALBUMEN AND CASEIN. 

flour, in tlie way already described. It is insoluble in water, 
partly soluble in alcohol, which extracts from it a fatty oil, and 
entirely and easily soluble in vinegar, (acetic acid,) or in solu- 
tions of caustic potash or soda. Besides the fatty oil which it 
contains, the crude gluten, as it is washed from wheaten 
flour, consists of at least two substances, — one soluble in alco- 
hol, {gliitin,) the other insoluble in this liquid, (gluten,) and 
which appears closely to resemble coagulated albumen. When 
moist, gluten is nearly colorless, and is tenacious and adhesive 
like bird-lime ; but when perfectly dry, it is hard, brittle, and 
of a grey or brownish color. 

2°. Alhumcn. — The white part of eggs is called albumen by 
chemists. In the natural state it is a glairy thick liquid, which 
can be diffused through or dissolved in v.- ater, but Avhich coagu- 
lates, or becomes solid and opaque, when heated to about 180° 
of Fahrenheit, or nearly to the temperature of boiling water. 
In this coagulated state it is insoluble in water, or in alcohol, 
but dissolves in vinegar, or in solutions of caustic potash or soda. 
When dried it becomes hard, brittle, semi-transparent, and of 
a brownish color. 

When the expressed juice or sap of plants is heated, a solid 
substance coagulates, and separates from it in opaque white 
flocks. This substancfe possesses nearly all the properties of the 
albumen of the q^^, and is therefore called vegetable albumen. 

Albumen exists in plants not only in the liquid state, as in 
the sap of plants, but also in the coagulated state. In the 
husks and envelopes of many seeds — the bran of corn for exam- 
ple — and in the solid parts of woody and herbaceous plants, it 
is found in this state in greater or less proportion. 

3°. Casein. — ^When rennet, vinegar, or diluted muriatic 
acid is added to milk, it coagulates or ci^i'dles, and a white curd 
separates from the whey. Alcohol or ether extracts the fat or 
butter from the coagulated mass, and leaves pure curd behind. 
To this curd chemists give the name of casein. 

When cold water is shaken up with oatmeal for half an hour, 



GERMIXATION OF SEEDS. 4T 

and is then allowed to subside, the clear liquid becomes troubled 
on the addition of a little acid, and a white powder falls, pos- 
sessing nearly all the properties of the casein of milk. 

The sap of nearly all plants — the expressed juice of the po- 
tato, the turnip, and other roots, after being heated to coagu- 
late the albumen — and the solution obtained when the meal of 
the bean, the pea, and other legumes, is treated with warm 
water — yield, on the addition of an acid, precipitates of this 
substance differing but httle from one another. 

Vegetable casein, therefore, is a constant constituent of our 
best known and cultivated plants. To the variety obtained 
from the oat the name of avenin has been given, and to that 
yielded by the bean, the pea, and the vetch, the name of Icguviin. 

All these substances arc combinations of a body called protein, 
and are therefore frequently spoken of under the general desig- 
nation of prGtein compounds/'^ They occur mixed in variable 
proportions in the different kinds of grain and roots which are 
used for food. In addition to carbon, oxygen, and hydrogen, 
they all contain, when quite dry, about 1 6 per cent of nitrogen, 
with 1 or 2 per cent of sulphur, and most of them also a small 
per-ceutage of phosphorus. 

SECTION VII. OF THE GERMINATION OF SEEDS AND THE GROWTH 

OF PLANTS. 

When a seed is committed to the earth, if the warmth and 
moisture are favorable, it begins to sprout. It pushes a 
shoot upwards, it thrusts a root downwards, but, until the leaf 
expands and the root has fairly entered the soil, the young plant 
derives no nourishment other than water, either from the earth 
or from the air. It lives on the starch and gluten contained in 
the seed. But these sub'stances, though capable of *being sepa- 
rated from each other by means of water, as described in a 

* For an account of protein and its compounds, see my Lectures on Acjri- 
cultural Chemistry^ 2d edition, p. 5. 



48 CHANGE OF STARCH INTO SUGAR. 

previous section, (p. 40,) are neither of tliem soluble in water. 
Hence they cannot, without undergoing a previous chemical 
change, be taken up into the sap and conveyed along the ves- 
sels of the young shoot they are destined to feed. But it is so 
arranged in nature that, when the seed first sprouts, there is 
produced at the base of the germ, from a portion of the gluten, 
a small quantity of a white soluble substance called diastase. 
This substance exer,cises so powerful an effect upon the starch 
as almost immediately to render it soluble in the sap, which is 
thus enabled to take it up and convey it by degrees, just as it is 
wanted, to the shoot or to the root.* The starch, when thus 
changed and rendered soluble, becomes the substance called 
dextrin, which we have already described, (p. 42.) 

In the oily seeds which contain no starch, the mucilage and 
the oil take the place of starch in nourishing the young sprout. 

As the sap ascends it becomes sweet — the dextrin formed 
from the starch is further changed into sugar. When the shoot 
first becomes tipped with green, this sugar again is changed 
into cellulose or woody fibre, of which the stem of perfect 
plants chiefly consists. By the time that the food contained in 
the seed is exhausted — often long before — the plant is able to 
live by its own exertions, at the expense of the air and the soil. 

This change of the sugar of the sap into cellular or woody 
fibre is observable more or less in all plants. When they are 
shooting fastest the sugar is most abundant — not, however, in 
those parts which are actually shooting up, but in those which 
convey the sap to the growing parts. Thus the sugar of the 

* In malting barley, it is made to sprout a certain length, and the growth 
is then arrested by heating and drying it. Mashed barley, before sprout- 
ing, will not dissolve in water; but when sprouted, the whole of the starch 
(the flour) it contains dissolves readily by a gentle heat, and is changed into 
soluble dextrin. The diastase formed during the germination effects this. 
By further heating in the brewer's wort, this dextrin is converted into sugar 
by the agency of the same diastase, as it is also in the growing plant. Wo 
can thus imitate by art ; and, in brewing, we do imitate what takes place 
naturally m the living vegetable. 



FORMATION OF CELLULAR FIBRE. 49 

ascending sap of the maple and the alder disappears in the leaf 
and in the extremities of the twig. Thus the sugar-cane sweet- 
ens only a certain distance above the ground, up to where the 
new growth is proceeding ; and thus also the young beet and 
turnip abound most in sugar — while in all these plants the 
sweet principle diminishes as the year's growth draws nearer to 
a close. 

In the ripening of the ear, also, the sweet taste at first so 
perceptible in young grain gradually diminishes, and finally dis- 
appears. The sugar of the sap is here changed into the sfarck 
of the grain, which, as above described, is afterwards destined, 
when the grain begins to sprout, to be reconverted into sugar 
for the nourishment of the rising germ. 

In the ripening of fruits a different series of changes presents 
itself. The fruit is at first tasteless, then becomes sour, and at 
last sweet. In this case, either the acid of the unripe is changed 
into the sugar of the ripened fruit, or a portion of the other 
constituents of the fruit — its cellulose and pectose — are con- 
verted into sugar, and disguise the acid. 

SECTION VIII. HOW THE CELLULAR OR WOODY MATTER OF 

PLANTS IS FORMED FROM THEIR ORGANIC FOOD, 

The substance of plants — their solid parts, that is — consists 
chiefly, as we have already stated, of cellular- fibre, the name 
given to the fibrous substance of which wood evidently consists. 
It is interesting to inquire how this substance can be formed 
from the compounds — water and carbonic, humic, ulmic, and 
other acids — of which the organic food of plants in a great 
measure consists. Nor is it difficult to find an ansv/er. 

1°. It will be recollected that the leaf drinks in carbonic 
acid from the air, and delivers back its oxygen, retaining only 
its carbon, (p. 38.) It is also known that water abounds iu 
the sap. Hence carbon and water are abundantly present iu 
the pores or vessels of the green and living leaf. Now, as cel- 
3 



50 FORMATION OF CELLULAR FIBRE, 

lulose or woody fibre consists ctily of carlcn and water chemically 
combined together, it is easy to see how, when the carlion and 
water meet in the leaf, cellular fibre may be produced by their 
mutual combination. 

2°. If, again, we inquire how this important constituent of 
plants may be formed from the other substances, which enter 
jjy their roots — from the humic acid (p. 21) for example — the 
answer is equally ready. This acid also consists of carbon and 
water only — 50 lb. of carbon with 37J of water forming 8tJ of 
humic acid — so that, when it is conveyed by the roots into the 
sap of the plant, all the materials are present from which the 
cellular fibre may be produced. 

3°. Nor is it more difficult to understand how the starch of 
the seed may be converted into sugar, and this again into cel- 
lular, fibre ; or how, conversely, sugar may be changed into 
starch in the ear of corn, or cellular fibre into sugar during the 
ripening of the winter pear after its removal from the tree. 
Any one of these substances may he represented by carbon and 
water only. In the interior of the plant, therefore, it is obvious 
that if any one of them is present in the sap, the elements are 
at hand out of which any of the others may be produced. In 
what way they really are produced, the one from the other, 
and by what circumstances these transformations are favored, 
it would lead into too great detail to attempt here to explain.* 

We cannot help admiring the varied purposes to which in 
nature the same elements are applied, — ^and from how small a 
number of materials, substances the most varied in their pro- 
perties are in the living vegetable daily produced. 

* For fuller and more precise explanations ou tliese interesting topics, 
see the Author's Lectures on Agricultural Chemistry aiid Geology, 2d edition, 
Part I. 



NECESSITY OF NITROGEX TO THE GROWTH OF PLANTS. 51 



SECTION IX. OF THE NECESSITY OF NITROGEX, OR OF SUBSTANCES 

CONTAINING IT, TO THE GROWTH OF THE PLANT, AND OF THE 
FORMS IN WHICH IT MAY ENTER THE ROOTS. 

But a substance containing nitrogen is necessary to the pro- 
duction of those beautiful and varied changes which take place 
in the sap of the plant at the different stages of its growth. 

We have seen that, during germination, the insoluble gluten 
of the seed is partly changed into a soluble substance — diastase 
— by which the first alteration of the insoluble starch into solu- 
ble dextrin is effected. The remainder of the gluten ascends 
or descends by degrees with the sap, in some soluble form which 
is not yet clearly understood, and, if not actually the cause of 
the successive changes which the starch, sugar, and gum of 
the sap undergo, it is at least always present when they are 
produced. 

At every point in the growings shoot and root some compound 
of nitrogen must be present, if it is to increase in size, — since 
in the interior of every new cell the presence of such a com- 
pound in minute quantity can be distinctly recognised. In the 
young radicles of the sprouting barley there are 32 per cent, of 
a substance containing nitrogen, while the grain itself contains 
only 14. This substance seems to preside over the change of 
the soluble substances contained in the sap, into the insoluble 
fibre of the cell. The change of the sugar and gum of the 
sap into the starch of the ear always takes place also in the 
presence of a substance containing nitrogen. In the young 
seed it is present in much larger proportion than when the seed 
is matured. In the pea, when beginning to form in the shell, it 
constitutes 48 per cent, of the whole weight, (Payen,) while in 
the ripe pea it does not exceed one-half the quantity. 

When the starch or sugar undergoes a change, the nitrogen- 
ous compound undergoes a simultaneous change ; and as the 
. transfoi-mation of the starch of the seed into the sugar of the 



52 FORMS IN WHICH NITROGEN ENTERS INTO PLANTS. 

sap is attended by the change of its gluten into diastase and 
other soluble compounds, so the converse change of the sugar 
of the sap into the starch of the ear is attended by a converse 
production of the insoluble gluten of the ripening grain. 

It has also been ascertained that the leaves of growing plants 
are in the sunshine always giving off nitrogen, in quantity which 
varies with the kind, and probably the age, of the plant, and 
with the time during which it has been exposed to the sun's 
rays. This nitrogen appears to be derived from gluten and 
other nitrogenous (protein) compounds, which are continually 
undergoing changes in the sap, and which arc necessary to the 
ordinary processes of vegetable grow^th. 

The necessity of nitrogen to the growth of the plant in all 
its stages is thus fully established ; and hence the utility, estab- 
lished by long practical experience, of applying manures in 
which nitrogen is contained. 

It has not yet been proved in what form of combination 
nitrogen is most fitted to promote the growth of our cultivated 
crops. It usually jBnds its way into the roots of plants in the 
form of nitric acid, of amntonia, of other organic alkalies con- 
taining nitrogen, (p. 30.) or of the compounds of these alkalies 
with the humic and ulmic acids, which are so extensively pro- 
duced in the soil itself. Animal manures may owe part of their 
peculiar beneficial action to their supplying other compounds of 
nitrogen — protein compounds, perhaps, in a soluble form — which 
the plant, with still less trouble to itself, can convert into por- 
tions of its own substance. 

The plant grows rapidly by the aid of the ready-formed 
gluten of the seed, — why should it not thrive well also by the 
aid of similar compounds placed within its reach in the soil and 
absorbed by its roots ? There seems, indeed, very little solid 
foundation for the opinion held by some, that the plants in our 
cultivated fields derive the ichoh of their nitrogen from ammonia 
and nitric acid together — still less that they obtain it from 
ammonia alone. 



FORMS IN WHICH NITROGEN MAY ENTER ROOTS. 53 

The plant that grows on the surface of common vinegar, and 
makes it thick and glairy, is formed from the vinegar* itself, 
and from a nitrogenous substance resembling gluten, which the 
liquid vinegar holds in solution. So the mould which grows on 
flour paste is formed from the starch and the gluten of the flour, 
and the minute j^lant which forms the yeast in the brewer's vat 
is produced from the sugar of the wort and the changed gluten 
of the barley.' 

In all these cases the substance of the plant is formed by the 
direct appropriation of compounds, which bear a close analogy 
to those of which its own parts consist ; and though the mould 
plants above mentioned are very different in kind from those we 
raise for food, yet the mode in which they are built up is very 
similar to that by which the solid parts of larger plants are 
really produced from the substances contained in the sap. If, 
then, those substances from which their growing parts are thus 
known to be built up can be conveyed directly into the circula- 
tion of our cultivated plants by their roots, it is reasonable to 
suppose that their growth may be promoted by them at least as 
well as if the roots took up only carbonic acid to supply the car- 
bon, and ammonia to supply the nitrogen. 

In other words, the probabihties are, I think, in favor of the 
view that animal or vegetable substances containing nitrogen, 
when brought into a soluble state by fermentation, may enter 
directly into the roots, and feed our crops, without being first 
decomposed either into ammonia or into nitric acid. The subject 
is deserving, therefore, of being made matter of direct experi- 
ment in the field or garden. 

* Pure vinegar, like starch and cellular fibre, consists of carbon and 
water alone, 50 of carbon and 56 of water forming 106 of vinegar. 



CHAPTEK TV. 

Of the iDorganic constituents of plants. — Potash, soda, Hme, magnesia, sihca, 
alumina, oxide of iron, oxide of manganese, sulphur, sulphuric acid, phos- 
phorus, phosphoric acid, chlorine, iodine, fluorine. — Immediate source of 
these constituents of plants. — The quantity contained in plants, and iu 
parts of plants, varies with many circumstances. — The composition or 
quality of the inorganic constituents in plants. — It varies also with many 
circumstances. — Average quantity of each constituent in certain common 
crops, and in a series of crops. — Practical deductions from a knowledge 
of the inorganic constituents of plants, 

SECTION I. SOURCE OF THE EARTHY MATTER OF PLANTS, AND 

SUBSTANCES OF WHICH IT CONSISTS. 

When plants are burned, they always leave more or less of 
ash behind. This ash varies in quantity in different plants, in 
different parts of the same plant, in different specimens even of 
the same kind, and of the same part of a plant, especially if 
grown upon different soils ; yet it is never wholly absent.* It 
is as necessary to theii' existence in a state of perfect health, as 
any of the elements which constitute the organic or combustible 
part of their substance. They must obtain it, therefore, along 
with the food on which they live. It is, in fact, a part of their 
natural food, since without it they become unhealthy. We shall 
speak of it, therefore, as the inorganic food of plants. 

We have seen that all the elements which are necessary to 
the production of the cellular fibre, and of the other organic 
parts of the plant, may be derived either from the air, from the 
carbonic acid and watery vapor taken in by the leaves, or from 

* The only known exceptions occur in the mould plants — as in the myco- 
derma vini, which grows on pure vinegar, that which groves on solutions of 
milk sugar, &c. By these no trace of ash is left. 



INORGANIC OR EARTHY MATTER OF PLANTS. 55 

the soil tlirougli the medium of the roots. In the air, however, 
only rare particles of inorganic or earthy matter are known to 
float, and these are in a solid form, and therefore unable to en- 
ter tlie minute pores of the leaves. Hence the earthy matter 
which constitutes the asli of plants must all be derived from the 
soil. 

The earthy part of the soil, therefore, serves a double use. It 
is not, as some have supposed; a mere substratum, in which the 
plant may so fix and root itself as to be able to maintain its up- 
right position against tlie force of winds and tempests ; b-ut it is 
a storehouse of food also, from which the roots of the plant may 
select such eartliy substances as are necessary to, or are fitted 
to promote, its growth. 

The ash of plants consists of a mixture of several, sometimes 
of as many as fourteen, different substances.. These substances 
are the following : — 

1. Potash. — The common pearl-ash of the sliops is a com- 
pound of potash with carbonic acid, or it is a carhoiiate of j)otash. 
By dissolving the pearl-ash in water, and ]joiHng it with quick- 
lime, the carbonic acid is separated, and potash alone, or caus- 
tic potash, as it is often called, is obtained. 

2. Soda. — Tlie common soda of the sho})S is a carlciiate of 
soda. By l.oiling it with quick-lime, the carbonic acid is sepa- 
rated, as in the case of peai'1-ash, and pure or caustic soda re- 
mains. The proportions to lie used are 1 li). of the carbonate 
to a I lb. of lime and 10 lb. of water. 

3. Lime. — This is familiar to every one as the Ume-shdls, or 
unslaked lime of the lime-kilns. The unburned lime-stone is a 
carbonate of lime, the carbonic acid in tliis case being separated 
from the lime by tlie roasting in the kiln. 

4. Magnesia. — This is the calcined magnesia of the shops. 
The uncalcined is a carbonate of magnesia, from which heat 
drives off the carbonic acid. 

5. Silica. — This is the name given by chemists to the sub- 
stance of flint, of quartz, of rock crystal, and of siliceous sands 



66 OXIDES OF IRON, MANGANESE, &C. 

and sandstones. It is particularly abundant in the straws and 
grasses, and in the glaze of the bamboo and other canes. 

6. Alumina is the pure earth of alum, obtained by dissolving 
alum in water, and adding liquid ammonia (hartshorn) to the 
solution. It forms about two-fifths of the weight of porcelain 
and pipe-clays, and of some other very stiff kinds of clay. It 
exists abundantly in most soils, but as an essential constituent 
of plants it has hitherto been met with only in the ash of the 
club mosses. 

1. Oxide of iron. — The most familiar form of this substance is 
the rust that forms on metallic iron in damp places. It is a 
compound of iron with oxygen, hence the name oxide. 

There are, however, two oxides of iron. The red, which gives 
its color to rust and to our red soils. This oxide is insoluble in 
water, and has the property of absorbing ammonia to a certain 
extent. 

The Hack oxide gives their color to many blue clays. It is so- 
luble in weak acids, is produced from the red oxide by the ac- 
tion of organic matter in the soil, and is believed, when so pro- 
duced, to be very noxious to the roots of plants. 

8. Oxide of manganese is a dark brown powder, which con- 
sists of oxygen in-combination with a metal resembling iron, to 
which the name of manganese is given. It usually exists in 
plants and soils in very small quantity only. 

9. Sulphur.- — This substance is well known. It is present in 
nearly all the parts of plants and animals. It exists largely in 
mustard seed, is a necessary constituent of the gluten of wheat, 
of the white of the egg, of the fibre of beef, and of the curd of 
milk, and forms one-twentieth part of the weight of hair and 
wool. When sown along with turnip seed, it is said to prevent 
the attack of the fly. 

Sulphuric Acid, or oil of vitriol, has been already described. 
It forms, with potash, sulphate of potash ; with soda, sulphate of 
soda, or Glauber's salts; with ammomsi, sulphate of ammo7iia ; 
with lime, sulphate of lime, or gypsum 5 with magnesia, sulphate 



PHOSPHORUS AND CHLORINE. 5t 

of magnesia, or Epsom salts ; with alumina, sulphate of alumina, 
which exists in alum ; and with oxide of iron, sulphate of iron, 
or green vitriol. When the sulphate of potash is combined with 
sulphate of alumina, it forms common alum. 

10. Phosphorus and phosphoric acid have been already de- 
scribed, (pp. 9 and 33.) 

Phosphoric acid forms phosphates with potash, soda, ammonia, 
lime, and magnesia. When bones are burned, a large quantity 
of a white earth remains, (bone earth,) which is chiefly a phos- 
phate of lime, consisting of lime and phosphoric acid, in the 
proportion of 48-| of phosphoric acid to 51| of lime. Phosphate 
of lime is present in the ash of plants generally. Phosphate of 
magnesia is contained most abundantly in the ash of wheat, 
barley, and other varieties of grain. It exists also in beer, to 
the amount sometimes of 100 grains in a gallon. 

11. Chlorine. — This is a very suffocating gas, of a pale, yellow- 

Fisr. 14. 



ish green color, which gives its peculiar smell to chloride of 
lime, and is used for bleaching and disinfecting purposes. It is 
readily obtained by pouring muriatic acid (spirit of salt) upon 
the black oxide of manganese of the shops, contained in a flask, 
and applying a gentle heat, as in the annexed figure. If the 
flask be of colorless glass, the color of the gas will immedi- 
3* 



68 IODINE AND BROMINE. 

ately become perceptible, and its smell will diffuse itself through 
the room. This gas is 2 J times heavier than common air, and 
a burning taper plunged into it is speedily extinguished. In 
combination with the metallic bases of potash, soda, lime, and 
magnesia, it forms the chlorides of potassium, sodium,) common 
salt), calcium, and magnesium ;* and in one or other of these 
states it generally enters into the roots of plants, and exists in 
their ash. 

Iodine is a solid substance of a grey color and metallic lus- 
tre, very much resembling filings of lead. It has a peculiar 
odor, not unlike that of chlorine, an acrid taste, and stains the 
fingers of a brown color. It is distinguished by two proper- 
ties — by being changed into a beautiful violet vapor when 
heated, and by giving with starch a beautiful blue compound. 
It occurs in small quantities in sea water, and in marine and 
many fresh-water plants. In still smaller proportion, it has 
been recently detected in wood ashes and in those of land plants, 
and it probably forms a constant though very minute constitu- 
ent of all the plants we raise for food. 

Like their chlorine, they will obtain it generally from the 
soil through their roots, though, as it has been detected in the 
atmosphere, they may derive some of this element from the rain 
water that falls on their leaves. 

Bromine is a dark brownish red heavy liquid, possessed of a 
strong odor, giving a yellowish red vapor, and coloring 
starch yellow. It also exists in sea water, in certain salt 
springs, and has been detected in the ashes of certain plants. 
It probably accompanies chlorine and iodine into all plants, 
though the proportion, which is still less than that of iodine, 
has hitherto prevented its presence from being detected. 

* Potash, soda, lime, and magnesia, are compoands of the metals hero 
named with oxygen. It is a very striking fact, that the suffocating gas 
chlorine, wlien combined with sodium, a metal which takes fire when 
placed upon hot water, should form the agreeable and necessary condiment 
common salt. 



VARIATION IN THE QUANTITY OF ASH IN PLANTS. 59 

As chlorine forms chlorides, so iodi7ie forms iodides, and bromine 
forms bromides with the metals ah'eady mxeutioned. The chlo- 
rine is the only one of these three, the presence of which in 
plants is at present believed to be of any importance in a prac- 
tical point of view. 

Fluorine is a very corrosive gas, of which little is yet known. 
It exists in small quantity in the teeth and bones, and in the 
blood and milk,' of animals. Traces of it also have been detect- 
ed in the ashes of some plants ; so that it is probably necessary 
to the growth of both animals and vegetables. With metals, 
it forms fluorides.; and fluoride of calcium, or fluor spar, is the 
best known and most common of its combinations. 

Such are the inorganic substances usually found mixed or 
combined together in the ash of plants. It has already been 
observed, that the quantity of ash left by a given weight of 
vegetable matter varies with a great many conditions. This 
fact deserves a more attentive consideration. 

SECTION II. OF THE DIFFERENCES IN THE QUANTITY OF ASH 

LEFT BY PLANTS, AND BY THEIR SEVERAL PARTS. 

1. The quantity of ash yielded by different jplants is unlike. 
Thus 1000 lb. of the following vegetable substances, in their 
ordinary state of dryness, leave of ash, on an average, 



Wheat, 


about 20 lb. 


Wheat straw, 50 lb. 


Barley, 


- 30 


Barley straw, 50 


Oats, 


- 40 


Oat straw, 60 


Eye, 


- 20 ' 


Rye straw, 40 


Indian corn, 15 


Indian corn do. 50 


Beans, 


- 30 


Pea straw, 50 


Peas, 


. 30 






Meadow hay, - 


50 to 100 lb. 




Clover h'ay, 


. 90 




Rye-grass hay, 


- 95 




Potatoes, 


8 to 15 




Turnips, 


5 to 8 




Carrots, 


- 15 to 20* 



* See Lectures on Agricultural Chemistry and Geology. 



60 VARIATION IN THE QUANTITY OF INORGANIC MATTER, &C. 

So that the quantity of inorganic food required by different 
vegetables is greater or less according to their nature : and if 
a soil be of such a kind that it can yield only a small quantity 
of this inorganic food, then those jilants only will grow well 
upon it to which this small supply will prove suiTiflent. Hence 
trees may grow where arable crops fail to thrive, because many 
of the former require and contain comparatively little inorganic 
matter. Thus the weight of ash left by 1000 lb. of 

Elm wood is 19 lb. Birch wood is 3), lb. 

Poplar, - 20 Pine, - 1^ to 3 

Willow, - 4 J Oak, - 2 

Beech, - l^o 6 Ash, - 1 to G 

The elm and the poplar contain about as much inorganic 
matter as the grain of wheat, but very much less than any of 
the straws or grasses. How much less also does the oak con- 
tain than either the elm or the poplar ! 

2. The quantity of inorganic matter varies in different parts 
of the same pkmt. This is shown clearly by the different pro- 
portions of ash left by the grain and by the straw of our culti- 
vated crops, as given in the preceding table. It appears, also, 
by the following comparison of the quantities left by 1000 lb. of 
the different parts of some of our cultivated plants in their dry 
state. Thus — 



R 


30ts or tuber. 


Grain or 


seed. 


Straw or stalks. 


Leaves. 


Turnip, 


80 1b. 


25 1b 




— lb. 


130 lb. 


Potato, 


40 " 


— 







180 " 


Wheat, 


— 


20 " 




50 '•' 




Pea, . . 


— 


30 " 




50 " 


130 " 


Tobacco, . 


*f0 " 


40 " 




100 " 


230 " 



In trees, also, the leaves contain a much larger proportion of 
inorganic matter than the wood. Thus, 1000 lb. of the dry 
wood and leaves of the following trees left of ash respectively — 

Seed. 



WiUow, 
Beech, . 


Wood. 
. 4i lb. 
. 4 " 


Leaves. 
82 1b. 
42 " 


Birch, . 
Pine, . 
Elm, . 


. 3 " 

. 19 " 


50 " 
20 to 30 
120 



50 1b. 



IT VARIES ALSO WITH THE SOIL. 61 

It appears, therefore, that by far the largest proportion of 
the inorganic matter which is withdrawn from the soil by a crop 
of corn is returned to it again, by the skilful husbandman, in 
the fermented straw. In the same way also nature, in causing 
the trees periodically to shed their leaves, returns with them to 
the soil a very large portion of the soluble inorganic substances 
which had been drawn from it by their roots during the season 
of growth. 

Thus an annual top-dressing is naturally given to the land 
where forests grow; and that which the roots from spring to 
autumn are continually sucking up, and carefully collecting from 
considerable depths, winter strews again on the surface in the 
f j-m of decaying leaves, so as, in the lapse of time, to form a 
ricn and fertile soil. Such a soil must be propitious to vegeta- 
ble growth, since it contains or is made up of those very mate- 
rials of which the inorganic substance of former races of vege- 
tables had been almost entirely composed. 

3. It varies in quantity in different portions of the same part 
of the plant. Thus, if a tall stalk of wheat, oats, or barley 
straw be cut into four equal parts, and these be burned sepa- 
rately, the lowest portion will generally leave the smallest, the 
highest portion the greatest per centage of ash. If the bottom 
of the stalk, for example, leave 3| or 4 per cent., the next por- 
tion will leave 5 or 6, the third 6 or t, and the highest perhaps 
8 or 9. This is a very interesting and curious fact, not hitherto 
noticed by experimenters, though evidently of great interest hi 
connection with the inorganic food of plants. 

In some cases this difference is not observed, while in others 
the largest proportion of ash is left by the bottom part of the 
straw. These exceptions, however, occur generally in stunted 
grain, which has grown upon an unfavorable soil, or has been 
injured by the season. 

4. The quantity of inorganic matter often differs in different 
speciinens and varieties of the same plant. Thus 1000 lb. of wheat 
straw, grown at different places, gave to four different experi- 



62 DIFFERS WITH VARIETY AND SOIL. 

menters 43, 44, 35, and 155 lb. of ash respectively. Wheat 
straw, therefore, does not always leave the same quantity of 
ash. The same is true also of other kinds of vegetable pro- 
duce. 

This fact, as well as the variation of the quantity of ash with 
the part of the plant, is shown by the following table of the 
proportions of ash left by the several parts of two different 
varieties of oats grown on different soils, (Norton) — 

Hopeton oat. Potato oat. 
2.14 2.22 

6.47 6.99 

4.98 8.62 



Grain, 

Husk, 

Straw, 

Leaf, 

Chafe, 



8.44 14.59 

16.53 18.59 



Here not only do the different parts of the same plant, but 
similar parts also of different plants of the same species, leave 
very different proportions of ash. 

To what is this difference owing ? Is it to the nature of the 
soil, or does it depend upon the variety of wheat, oats, or other 
produce experimented upon ? It seems to depend partly upon both. 

a. Variety. — Thus on the same field, in Ravensworth Dale, 
Yorltshire, on a rich clay soil abounding in lime, the Golden 
Kent and Flanders Bed wheats were sov/n in the spring of 1841. 
The former gave an excellent crop, while the latter was a total 
failure, the ear containing 20 or 30 grains only of poor wheat. 
The straw of the former left 165 lb. of ash from 1000 lb., that 
of the latter only 120 lb. Something, therefore, dejpends upon 
the variety. 

b. Soil. — Again, 1000 lb. of the straw of the same variety of 
oat, grown by the Messrs. Drummond of Stirling in 1841, upon 

Aberdeen granite, left 96 lb. of ash. 



On clay-slate, 


18 


On greenstone, 


79 


On limestone, 


102 


On gypsum, 


58 


On silicious S9.nd, 


64 


On light loamy soil. 


88 



GENERAL CONCLUSION, 63 

The quantity of ash, therefore, depends in some measure also upon 
the nature of the soil. 

5. But the degree of ripeness which a plant has attained has 
also an influence on the i)roportion of ash which it leaves. 
Thus the straw of the same wheat grown on the same limestone 
soil near Wetherby, in Yorkshire, gave me, when cut five weeks 
before it was ripe, 40 lb., and when fully ripe, 55 lb., from 1000 
lb. of dry straw.' To compare the ash, therefore, of any two 
samples of straw, they ought to be gathered in the same state 
of ripeness. 

A similar observation also has been made in regard to the 
wood of trees. The quantity of ash they leave varies both 
with their age and with the season of the year at which they 
are burned. 

On the whole, the truth, so far as it can as yet be made out, 
seems to be this — that every plant must have a certain quantity 
of inorganic matter to make it grow in the 7uost healthy manner 
• — that it is capable of living, growing, and even ripening seed 
with much less, and probably with much more, than this quan- 
tity — ^but that those soils will produce the most perfect plants 
wdiich can best supply all their wants; and that the best seed 
will be raised in those districts wdiere the soil, without being 
too rich or rank, yet can yield both organic and inorganic food 
in such proportions as to maintain the corn plants in their most 
healthy condition. 

This latter observation, in regard to the quality of seed, is 
of great practical importance, and must be borne in mind w^hen 
we come hereafter to inquire wdiether seeds can be so prepared 
or doctored, by steeping or otherwise, as to grow quicker, with 
more certainty, and with greater luxuriance, and to yield larger 
returns of grain. 



64 



THE QUALITY OF THE ASH OF FLANTS. 



SECTION III. OF THE COMPOSITION OR QUALITY OF THE ASH OF 

PLANTS, AND THE CIRCUMSTANCES BY WHICH IT IS MODIFIED. 



But much also depends upon the quality as well as upon the 
quantity of the ash. Plants may leave the same weight of ash 
when burned, and yet the nature of the specimens of ash — the 
kind of matter of which they respectively consist — may be very 
different. The ash of one may contain much lime, of another 
much potash, of a third much soda, while in a fourth much sili- 
ca may be present. Thus 100 lb. of the ash of hean straw have 
been found to contain 53 lb. of potash, while that of barley con- 
tained only 9 lb. in the hundred. On the other hand, 100 lb. 
of the ash of barley straw contain 68 lb. of silica, while in that 
of bean straw there are only *T 11). 

The quality of the ash seems to vary with the same conditions 
by which its quantity is affected. Thus — 

1. It varies with the kind of -plant. — 1000 lb. of the ash of the 
grain of wheat, barley, oats, beans, and linseed — of the potato 
tuber and the turnip bulb, for example — contain respectively — 



Potash, - 
Soda, 
Lime, 
Magnesia, 
Oxide of iron, - 
Phosphoric acid, 
Sulphuric acid. 
Silica, - 
Chlorine, - 




a 


O 


6 


.2 ^ 


G 
0) 


r3 


c 


p. 

5 

H 


237 

91 

28 

120 

1 

500 

3 

12 


136 

81 

26 

15 

15 

390 

1 

2t3 

trace. 


262 

60 

100 

4 

438 

105 

27 

3 


220 

116 

49 

103 

13 

495 

9 

4 


|-325 j 

14 

162 

3 

449 

28 

14 

2 


336 
106 

58 
80 

6 

380 

10 

12 

7 


245 

34 

147 

99 

19 

381 

9 

57 

3 


557 

19 

20 

53 

5 

126 

136 

42 

42 


419 
51 

136 
53 
13 
76 

136 
79 
36 


998 


997 


999 


1009 


997 


995 


994 


1000 


999 



A comparison of the numbers in the first four columns shows 
how unlike the quantities of the different substances are which 



THE ASH OF GRAINS AND BULB. 65 

are contaiued in an equal weight of the ash of the four varieties 
of grain. It is to be remarked, however, that the great differ- 
ence in the case of barley arises from the thick husk with which 
it is covered, and from which the large per centage of silica is 
derived. The sample of oats was taken without the husk. 

Beans contain more sulphuric acid, also, than any of the other 
grains in the above table, while they are deficient in phosphoric 
acid when compared with wheat, barley, or oats. But the most 
striking differences appear between the several kinds of grain 
and the potato and turnip. In these last the alkaline matter is 
very much greater, while the phosphoric acid is much dimin- 
ished. 

It is thus evident that a crop of wheat will carry off from the 
soil — even suppose the whole quantity of ash left by each to be 
the same in weight — very different quantities of potash, soda, 
lime, phosphoric acid, &c., from what would be carried off by a 
crop of beans or of potatoes. It will, therefore, exhaust the soil 
more of some, as beans and potatoes will of other substances. 
Hence one reason why a piece of land may suit one crop and not 
suit another. Hence, also, two successive crops of different 
kinds may grow well where it would greatly injure the soil to 
take two in succession of the same kind, especially of either 
wheat or barley ; and hence we likewise deduce one natural rea- 
son for a rotation of crops. The surface-soil may be so far ex- 
hausted of one inorganic substance that it cannot afford it in 
sufficient quantity to bring a given crop to healthy maturity ; 
and yet this substance may, by natural processes, be so far re- 
stored again, during the intermediate growth of certain other 
crops, as to be prepared in a future season fully to supply all 
the wants of the same crop, and to yield a plentiful harvest. 

2. The kind of inorganic matter varies with the 'part of the 
plant. — Thus the grain and the straw of the corn-plants contain 
very unlike quantities of the several inorganic constituents, as 
will appear by comparing the several columns in the following 
with those of the preceding table. 



66 



ASH OF STRAW. 



1000 lb. of the ash of the straio of wheat, barley, oats, rye, 
and Indian corn, have been found to contain respectively of — 



Potash, - - - 


Wheat. 


Barley. 


Oats. 


Eye. 


Indian 
corn. 


125 


92 


191 


173 


96 


Soda, - - - 


2 


3 


97 


3 


286 


Lime, - - - 


67 


85 


81 


90 


83 


Magnesia, - - 


.^9 


50 


38 


24 


66 


Oxide of iron, - 


13 


10 


IS 


14 


8 


Phosphoric acid, 


31 


31 


26 


38 


171 


Sulphuric acid,- 


58 


10 


33 


8 


7 


Chlorine, - - 


11 


6 


32 


5 


15 


Silica, - - - 


654 


676 


484 


645 


270 


1000 


963 


1000 


1000 


1012 



The quantities of the several inorganic substances contained 
in the above kinds of straw are very different from those con- 
tained in the corresponding kinds of grain. In this difference 
we see one reason why the same soil which may be favorable to 
the growth of the straw of the corn plant may not be equally 
propitious to the growth of the ear. The straw contains com- 
paratively little of some of the ingredieuts found in the ear, es- 
pecially of the lime, magnesia, and phosplioric acid, while the 
grain contains a large proportion of these substances. On the 
other hand, the straw is rich, and the grain very poor in silica. 
It is clear, therefore, that the roots may, in certain plants and 
in certain soils, succeed in fully nourishing the straw, while they 
cannot fully ripen the ear ; or contrariwise, where they feed but 
a scanty straw, may yet he ahle to give ample sustenance to the 
filling ear.* 

That similar differences prevail in other orders of plants also, 
and that their several parts require, therefore, different propor- 

* And occasionally do give ; for a plump grain, and even a ■well-filled ear, 
are not uu frequently found where tlie straw is unusually deficient. 



ASH OF THE APPLE TREE AND FRUIT. 



6t 

them to 



tions of the several kinds of inorgauic food to brin^ 
perfection, is shown by the following table. 

1000 lb. of the ash of the stem, leaves, and fruit of the apple 
tree, {Pyrus sjpectahilis — Chinese crab,) have been found to 
contain respectively, (Vogel,) 



Carbonates of potash and soda, 
Phosphates of do., - 
CaFbonate of lime, - 
Carbonate of mao-nesia, - 
Phosphates of hme and magnesia, 
Silica, 


Stem. 


Leaves 


Fruit. 


4G 

822 
49 
88 


68 

trace. 

729 

98 
105 


190 
141 
370 

55 
186 

37 


1005 


1000 


979 



Thus potash and phosphoric acid abound most in the fruit 
of the apple tree, as they do in the ear of our corn plants, and 
are therefore as necessary to their healthy grov/th and complete 
maturity. 

3. The quality of the. ash varies also with the hind of soil in 
which the plant is made to grow. — This will be understood from 
what has been stated above. Where the soil is favorable, the 
roots can send up into the straw everything which the plant re- 
quires for its healthy grow^th, and in the right proportions. 
When it is either too poorly or too richly supplied with one or 
more of those inorganic constituents which the plant desires, 
life may indeed be prolonged, but a stunted or unhealthy crop 
will be raised, and the kind, and perhaps the quantity, of ash 
left on burning it, will necessarily be different from that left by 
the same species of plant grown under more favoring circum- 
stances. Of this fact there can be no doubt, though the extent 
to which such variations may take place without absolutely kill- 
ing the plant has not yet been made out. That it is considera- 
ble is shown by the following table, which exhibits the compo- 



68 



INFLUENCE OF SOILAGE AND SEASON. 



sition of 1000 lb. of the ash of three samples of wheat grown in 
different localities : — 





Dutch. 


German. 




White. 


Red. 


Potash, .... 


64 


219 


338 


Soda, .... 


278 


157 




Lime, .... 


39 


19 


31 


Magnesia, 


130 


96 


136 


Oxide of iron, 


5 


14 


3 


Sulphuric acid. 


3 


2 




Pliosphoric acid. 


461 


493 


492 


Silica, .... 


3 




•• 




983 


1000 


1000 



In the first of these we find little potash, in the last no soda, 
while in all nearly half the weight consists of phosphoric acid. 

4. It varies also with the period of the planfs growth, or the 
season at which it is reaped — Thus, in the young leaf of the 
turnip and potato, a greater proportion of the inorganic matter 
consists of potash than in the old leaf. The same is true of the 
stalk of wheat; and similar differences prevail in almost every 
kind of plant at different stages of its growth. 

The enlightened agriculturist will perceive that all the facts 
above stated have a more or less obvious connection with the 
ordinary processes of practical agriculture, and tend to throw 
considerable light on some of the principles by which these pro- 
cesses ought to be regulated. One illustration of this is exhib- 
ited in the following section. 



SECTION IV. AVERAGE QUANTITY OF INORGANIC MATTER CONTAINED 

IN AN ORDINARY CROP, OR SERIES OF CROPS. 

The importance of the inorganic matter contained in living 
vegetables, or in vegetable substances when reaped and dry, 



WHAT A WHOLE CROP CARRIES OFF. 



69 



will appear more distinctly if we consider the actual quantity 
carried off from the soil in the series of crops. 

In a four years' course of cropping, in which the crops gathered 
amounted per acre to — 

1st year, Turnips^ 20 tons of bulbs and 63- tons of tops. 

2d year, Barley^ 40 bushels of 63 lb. each, and 1 ton of straw. 

3d year, Clover and Rye-Grass^ \h ton of each in hay. 

4th year, Wlieat, 25 bushels of GO lb., and 1| tons of straw. 

1°. The quantity of inorganic matter carried off in the four 
crops, supposing none of them to be eaten on the land, amounts 
to about — 



Potash, 


311 lb. 


Sulphuric acid, . 


108 lb. 


Soda, 


54 " 


Phosphoric acid 


116 " 


Lime, . 


193 " 


Chlorine, . 


TO " 


Magnesia, , 


55 " 






Oxide of iron, 


15 " 






Silica, 


356 " 


Total, 


1284 • 



or in all about 11 cwt.; of which gross weight the different sub- 
stances form unlike proportions. 

2°. A still clearer view of these quantities will be obtained by 
a consideration of the fact, that if we carry off the entire pro- 
duce, and add none of it again in the shape of manure, we must 
or ought, in its stead, if the land is to be restored to its original 
condition, to add to each acre every four years — 



Dry pearl-ash, 


465 lb 


Common bone dust. 


552 » 


Epsom salts. 


326 " 


Common-salt, 


116 " 


Quick-lime, . . . • 


70 " 



Total, 



1529 



Several observations suggest themselves from a consideration 
of the above statements. 

First, That if this inorganic matter be really necessary to the 
plant, the gradual and constant removal of it from the land 
ought, by and by, to make the soil poorer in this part of the 
food of plants. 



70 ' GENERAL CONSIDERATIONS. 

Second, That the more of the crops which grows upon the 
land we return to it again in the form of manure, the less will 
this deterioration be perceptible. 

Third, That as many of these inorganic substances — the 
potash, soda, &c., — are readily soluble in water, the Hquid ma- 
nure of the farmyard, so often allowed to run to waste, must 
carry with it to the rivers much of the saline matter that ought 
to be returned to the land. 

Fourth, If the rains also are allowed to run over and vmsk 
the surface of the soil, they will gradually deprive^t of those 
soluble saline substances which appear to be so necessary to the 
growth of plants. Hence one important benefit of a system of 
drainage so perfect as to allow the rains to sink into the soil 
where they fall, and thus to carry down, instead of away, what 
they naturally dissolve. 

And, lastly. That the utility, and often indispensable necessity, 
of certain artificial manures — though, in some districts, perhaps 
arising from the natural poverty of the land in some of the 
mineral substances which plants require — ^is most frequently 
owing to a want of acquaintance with the facts above stated, 
and to the long-continued neglect and waste which has been the 
natural consequence. 

In certain districts, the soil and subsoi] contain within them- 
selves an almost unfailing supply of some of these inorganic or 
mineral substances, so that the waste of them is long in being felt; 
in others, again, the land contains less, and therefore becomes 
sooner exhausted. This latter class of soils requires a more 
careful, and usually a more expensive mode of cultivation than 
the first; but both will become at length alike unproductive, if 
that which is yearly taken from the soil is not in some form or 
other restored to it. 

One thing is of essential importance to be remembered by the 
practical farmer — that the deterioration of land is often an ex- 
ceedingly slow process. In the hands of successive generations, 
a field may so imperceptibly become less valuable, that a cen- 



ARTIFICIAL MANURES, WHY NECESSARY. 11 

tury even may elapse before the change prove such as to make 
a sensible dhuinution in the valued rental. Such slow changes, 
however, have been seldom recorded; and hence the practical 
man is occasionally led to despise the clearest theoretical prin- 
ciples, because he has not happened to see them verified in his 
own limited experience; and to neglect, therefore, the sug- 
gestions and the wise precautions which these principles lay 
before him. 

The special agricultural history of known tracts of land of 
different qualities, showing how they had been cropped and tilled, 
and the average produce in grain, hay, and stock every five 
years, during an entire century, would aftbrd invaluable mate- 
rials both to theoretical and to practical agriculture. 

General illustrations of this sure though slow decay may be 
met with in the agricultural history of almost every country. 
In none, perhaps, are they more striking than in the older slave 
states of North America. Maryland, Yirginia, and North Ca- 
rolina — once rich and fertile — by a long-continued system of 
forced and exhausting culture, have become unproductive in 
many places, and vast tracts have been abandoned to appa- 
rently hopeless sterility. Such lands it is possible to reclaim, 
but at v»^hat an expense of time, labor, manvn-e, and skilful 
management ! It is to be hoped that the newer states will 
not thus sacrifice their future power and prospects to present 
and temporary wealth — that the fine lands of Ohio, Kentucky, 
and the Prairie states, which now yield Indian corn and wheat, 
crop after crop, without intermission and without manure, will 
not be so cropped till their strength and substance is gone, but 
that a better conducted and more skilful husbandry will con- 
tinue, without diminishing the 'present crops, to secure a per- 
manent fertility to that naturally rich and productive country. 

SECTION Y. PRACTICAL DEDUCTIONS TO BE DRAWN FROM A KNOW- 
LEDGE OF THE INORGANIC CONSTITUENTS OF PLANTS. 

Several important practical deductions are to be draT^^l from 



T2 PRACTICAL DEDUCTIONS. 

what lias been stated in regard to the inorganic constituents of 
plants. 

1"^. Why one crop may grow well where another fails. — Sup- 
pose, for example, a crop to require a peculiarly large supply 
of potash — it may grow well if the soil abound in potash ; but 
if the soil be deficient in potash and abound in lime, then this 
crop may scarcely grow at all upon it, while another crop to 
which lime is especially necessary may grow luxuriantly. 

2°. Why 7nixed crops groio tvell together. — If two crops of 
unlike kinds be sown together, their roots suck in the inorganic 
substances in different proportions — the one more potash and 
phosphoric acid perhaps — the other more lime, magnesia, or 
silica. They thus interfere less with each other than plants of 
the same kind do — which require the same kinds of food in 
nearly the same proportions. 

Or the two kinds of crop grow with different degrees of 
rapidity, or at different periods of the year ; and thus, while 
the roots of the one are busy drawing in supplies of inorganic 
nourishment, those of the other are comparatively idle ; and 
thus the soil is able abundantly to supply the wants of each as 
its time of need arrives. 

3°. Why tJiesame crop grows letter on the same soil after long 
i7itervals. — If each crop demands special substances, or these 
substances in quantities peculiar to itself, or in some peculiar 
state of combination, the chances that the soil will be able to 
supply them are greater, the more distant the intervals at 
which the same crop is grown upon it. Other crops do not 
demand the same substances, or in the same proportions ; and 
thus they may gradually accumulate on the soil till it becomes 
especially favorable to the particular crop we wish to grow. 

4°. Why a rotation of crops is necessary. — Suppose the soil 
to contain a certain average supply of all "those inorganic sub- 
stances which plants require, and that the same corn crop is 
grown upon it for a long series of years — this crop will carry 
off some of these substances in larger proportion than others, 



ROTATION OF CROPS : EXHAUSTION. 73 

SO that year by year the quantity of those which are thus 
chiefly carried off will become relatively less. Thus at length 
the soil, for want of these special substances, will become 
unable to bear a corn crop at all, though it may still contain a 
large store of the other inorganic substances which the corn 
crop does not specially exhaust. Suppose bean or turnip crops 
raised in like manner for a succession of years, they would 
exhaust the soil "of a different set of substances till it became 
unable to grow them profitably, though still rich perhaps iu 
those things which the corn crop especially demands. 

But grow these crops alternately, then the one crop will 
draw especially upon one class of substances, the other crop 
upon another ; and thus much larger crops of each will be 
reaped from the same soil, and for a much longer period of 
time. 

On this principle the benefit of a rotation of crops in au 
important degree depends.* 

5°. What is meant by exhaustion. — Thus, exhaustion may 
either be general, arising from the gradual carrying off of all the 
kinds of food on which plants live — or special, arising from the 
want of one or more pf those substances which the crops that 
have been long grown upon it have specially required. 

To repair the former kind of exhaustion, an addition of 
many things to the soil may be necessary ; — to repair the 
latter, it may be sufficient to add a needful supply of one 
or more things only. In showing how this may be most 
efficiently and most economically done, chemistry will be of 
the most essential service to >the practical man. Before en- 
tering further upon this point, however, it will be necessary to 
study also the nature of the soil in which plants grow. 

* In showing, in the above remarks, how the doctrine of the inorganic 
part of plants throws hght, among other things, upon the use of a rotation 
of crops, the reader will bear in mind that a knowledge of the organic por- 
tion of the plant, and of the living functions of each part in each species, is 
no less necessary to the full understanding of this intricate subject. 
4 



C H A P T E R V . 

Of soils. — Their organic and inorganic portions. — Saline or soluble, and 
earthy or insoluble, matter in soils. — Examination and classification of 
soils. — Determination of the per-centage of sand, clay, vegetable matter, 
and lime. — Diversities of soils and subsoils. 

Soils consist of two -parts ; of an organic part, which can 
readily be burned away when the soil is heated to redness ; and 
of an inorganic part, which is fixed in the fire, and which con- 
sists entirely of earthy and saline substances. 

SECTION I. or THE ORGANIC TART OF SOILS. 

The organic part of soils is derived chiefly from the remains 
of vegetables and animals which have lived and died in or upon 
the soil, which have been spread over it by rivers and rains ; or 
which have been added by the hands of man, for the purpose 
of increasing its natural fertility. 

This organic part varies very much in quantity in different 
soils. In some, as in peaty soils, it forms from 50 to 70 per 
cent of their whole weight ; and even in rich long-cultivated 
soils it has been found, in a few rare cases, to amount to as 
much as 25 per cent. In general, however, it is present in 
much smaller proportion, even in our best arable lands. Oats 
and rye will grow upon a soil containing only 1 J per cent, barley 
when 2 to 3 per cent are present, while good wheat soils gene- 
rally contain from 4 to 8 per cent. The rich alluvial soil of the 
valley of the Nile contains only 5 per cent of dry organic mat- 
ter. In stiff and very clayey soils, 10 to 12 per cent is some- 
times found. In very old ])asture-lands, and in gardens, vegeta- 
ble matter occasionally accumulates so as to overload the upper 
soil. 



ORGANIC AND INORGANIC PARTS OF THE SOIL. T5 

To this organic matter in the soil the name of humus has 
been given by some writers. It contains, or yields to the plant, 
the ulmic, humic, and other acids already described, (see Chap- 
ter II.) It supplies also, by its decay in contact with the air 
which penetrates the soil, much carbonic acid, which is supposed 
to enter the roots, and thus to assist the growth of living vege- 
tables. During the same decay, ammonia, as we have already 
stated, is likewise produced, and this in larger quantity if ani- 
mal matter be present in considerable abundance. Other sub- 
stances, more or less nutritious, are also formed from the organic 
matter in the soil. These enter by the roots, and contribute to 
nourish the growing plant, though the extent to which it is fed 
from this source is dependent, both upon the abundance with 
which these substances are supplied, and upon the nature of the 
plant itself, and of the climate in which it grows. 

Another influence of this organic portion of the soil, whether 
naturally formed in it or added to it as manure, is not to be 
neglected. It contains — as all vegetal)le substances do — a con- 
siderable quantity of inorganic, that is, of saline and earthy 
matter, Avhich is liberated as the organic part decays. Thus 
living plants derive from the remains of former races, Ijuried 
beneath the surface, a portion of that inorganic food which can 
only be obtained from the soil, and which, if not thus directly 
supplied, must be sought for by the slow extension of their roots 
through a greater depth and breadth of the earth in which they 
grow. The addition of manure to the soil, therefore, j^laces 
within the easy reach of the roots not only organic but also inor- 
ganic food. 

SECTION II. OF THE INORGANIC PART OF SOILS. 

The inorganic part of soils — that which remains behind, when 
everything combustible is burned away by heating it to redness 
in the open air — consists of two portions, one of which is sduhle 
in water, the other insoluble. Tlie soluble consists of saline sub- 
stances, the insoluble of carl/iy substances. 



76 SALINE OR SOLUBLE PART. 

1. The saline or soluble portion. — In this country, the surface- 
soil of our fields, in general, contains very little soluble matter. 
If a quantity of soil be dried in an oven, a pound weight of it 
taken, and a pint and a-half of pure boiling rain water poured 
over it, and the whole well stirred and allowed to settle, the 
clear liquid, when poured off and boiled to dryness, may leave 
from 30 to 100 grains of saline mixed with a variable quantity 
of organic matter. This saline matter will consist of common 
salt, gypsum, sulphate of soda, (Glauber's salts,) sulphate of 
magnesia, (Epsom salts,) with traces of the chlorides of calcium, 
magnesium, and potassium, and of potash, soda, lime, and mag- 
nesia, in combination with nitric and phosphoric, and with the 
humic and other organic acids. It is from these soluble sub- 
stances that the plants derive the greater portion of the saline 
ingredients contained in the ash they leave when burned. 

Xor must the quantity thus obtained from a soil be considered 
too small to yield the whole supply which a crop requires. A 
single grain of saline matter in even/ pound of a soil a foot deep, 
is equal to 500 lb. in an acre. This is more than is carried off 
from the soil in ten rotations, (forty years,) where only the 
wheat and barley are sent to market, and the straw and green 
crops are regularly, and without loss, returned to the land in 
the manure."^ 

In some countries — indeed, in some districts of our own coun- 
try — the quantity of saline matter in the soil is so great as in 
hot seasons to form a white incrustation on tlie surface. It may 
often be seen in the neighborhood of Durham ; and is more 
especially to be looked for in districts where the subsoil is sandy 
and porous, and more or less full of water. In hot weather, 
the evaporation on the surface causes the water to ascend from 
the porous subsoil ; and as this water always brings with it a 
quantity of saline matter, which it leaves behind when it rises 

* A furllier portion, it will be recollected, is carried off in the cattle tliat 
{ire sent to market, or is lost in the liquid manure that is wasted, or is washed 
out by the rains from the soil or from the manure ; all these are here neglected. 



SALINE INCRUSTATIONS UPON THE SOIL. 71 

in vapor, it is evident that, the longer the dry weather and 
conseqnent evaporation from the surface continue, the thicker 
the incrustations will be, or the greater the accumulations of 
sahne matter on the surface. Hence, where such a moist and 
porous subsoil exists in countries rarely visited by rain, as in the 
plains of Peru, of Egypt, or of India, the country is whitened 
over in the dry season with an unbroken snowy covering of the 
different sahne substances above mentioned. 

When rain falls, the saline matter is dissolved, and descends 
again to the subsoil. In dry weather it re-ascends. Hence the 
surface-soil of any field will contain a larger proportion of solu- 
ble inorganic matter in the micldle of a hot dry season than in 
one of even ordinary rain. Hence, also, the fine dry weather 
which, in early summer, hastens the growth of corn, and later 
in the season favors its ripening, does so probably, among its 
other modes of action, by bringing up to the roots from beneath 
a more ready supply of those saline compounds which the crop 
requires for its healthful growth. In some countries, however, 
this saline matter ascends in such quantity as to render the soil 
unfit to grow the more tender crops. Thus, on the plains of 
Attica, when the rainy season ends, saline substances begin to 
rise to the surface in such abundance as by degrees entirely to 
burn up or prevent the growth of grass, though abundant wheat 
crops are yearly ripened. 

2. T'he earthy or insoluble 'portion. — The earthy or insoluble 
portion of soils rarely constitutes less- than 95 lb. in a hundred 
of their whole weight. It consists chiefly of silica in the form 
of sand- — of alumina mixed or combined with silica in the form 
of clay — and of lime in the form of carhonate of lime. It is 
rarely free, however, from two or three per cent of oxide of 
iron ; and where the soil is of a red color, this oxide is often 
present in still larger proportion. A trace of magnesia also 
may be almost always detected, and a minute quantity of phos- 
phate of lime. The principal ingredients, however, of the 
earthy part of all soils are sand, clay, and lime ; and soils are 



78 SEPARATION OF SAND AND CLAY. 

named or classified according to the quantity of each of these 
three they may happen to contain. 

a. If an ounce of soil be intimately mixed with a pint of 
water till it is perfectly softened and diffused through it, and 
if, after shaking, the heavy parts be allowed to settle for a few 
minutes, the sand will subside, while the clay, which is in finer 
particles, and is less heavy — will still remain floating. If the 
water and fine floating clay be now poured into another vessel, 
and be allowed to stand till the water has become clear, the 
sandy part of the soil will be found on the bottom of the first 
vessel, and the clayey part on that of the second, and they 
may be dried and weighed separately. 

h. If 100 grains of dry soil, not peaty or unusually rich in 
vegetable matter, leave no more than 10 of clay when treated 
in this manner, it is called a sandy soil ; if from 10 to 40, a 
sandy loam ; if from 40 to tO, a loaTiiy soil ; if from 10 to 85, a 
clay loam ; from 85 to 95, a strong clay soil ; and when no sand 
is separated at all by this process, it is a pure agricultural clay. 

c. The strong clay soils are such as are used for making tiles 
and bricks ; the pure agricultural clay is such as is commonly 
employed for the manufacture of pipes, (pipe-clay.) This pure 
clay is a chemical compound of silica and alumina, in the pro- 
portion of about 60 of the former to 40 of the latter. Soils 
of pure clay rarely occur — it being well known to all practical 
men that the strong clays, (tile clays,) which contain from 5 
to 15 per cent of sand, • are brought into arable cultivation 
with the greatest possible difficulty. It will rarely, almost 
never, happen, therefore, that arable land will contain more 
than 30 to 35 per cent of alumina. 

d. If a soil contain more than 5 per cent of carbonate of 
lime, it is called a marl ; if more than 20 per cent, it is a cal- 
careous soil. Peaty soils, of course, are those in which the 
vegetable matter predominates very much. 

e. The quantity of vegetable or other organic matter is de- 
termined by drying the soil well upon paper in an oven, until it 



J 



DIVERSITIES OF SOILS AND SUBSOILS. 79 

ceases to lose weight — taking care that tlie heat is not so great 
as to char the paper — and then burning in the open air a 
weighed quantity of the dried soil : the loss by burning is 
nearly all organic matter. In stiff clays this loss will include 
also a portion of water, which is not wholly driven off from 
such soils by drying upon paper in the way described. 

/. To estimate the lime, a quantity of the soil should be 
heated in the air till the organic matter is burned away. A 
weighed portion, (200 or 300 grains,) should then be diffused 
through half a pint of cold water mixed with lialf a wine- 
glassful of spirit of salt, (muriatic acid,) and allowed to stand 
for a few hours, with occasional stirring. When minute bub- 
bles of gas cease to rise from the soil, the water is poured off, 
the soil dried, heated to redness as before, and weighed : the 
loss is nearly all lime. 

SECTIOX III. OF THE DIVERSITIES OF SOILS AND SUBSOILS. 

1st. Soils. — Though the substances of which soils chiefly con- 
sist are so few in number, yet every practical man knov/s how 
very diversified they are in character — how very different in 
agricultural value. Thus, in some of our southern counties, 
we have a white soil, consisting apparently of nothing else but 
chalk ; in the centre of England a wide plain of dark-red 
land ; in the border counties of Wales, and on many of our 
coal-fields, tracts of country almost perfectly black ; while 
yellow, white, and brown sands and clays give the prevailing 
character to the soils of other districts. Such differences as 
these arise from the different proportions in which the sand, 
lime, clay, a,nd the oxide of iron and organic matter which 
color the soils, have been mixed together. 

But how have they been so mixed — differently in different 
parts of the country ? By what natural agency ? For what 
end? 

2d. Subsoil. — Again, the surface-soil rests on what is usually 
denominated the subsoil. This is also very variable in its cha- 



80 IMPORTANCE OF THE SUBSOIL. 

racter and quality. Sometimes it is a porous sand or gravel, 
through which water readily ascends from beneath, or sinks in 
from above ; sometimes it is light and loamy, like the soil that 
rests upon it ; sometimes stiff, and more or less impervious 
to water. 

The most ignorant farmer knows how much the value of a 
piece of land depends upon the character of the surface-soil, — 
the intelhgent improver understands best the importance of a 
favorable subsoil. "When I came to look at this farm," said 
an excellent agriculturist to me, " it was spring, and damp, 
growing weather : the grass was beautifully green, the clover 
shooting up strong and healthy, and the whole farm had the 
appearance of being very good land. Had I come in June, 
when the heat had drunk up nearly all the moisture which the 
sandy subsoil had left on the surface, I should not have offered 
so much rent for it by ten shillings an acre." He might have 
said also, " Had I taken a spade, and dug down 18 inches in 
various parts of the farm, I should have known what to expect 
in seasons of drought." 

But how come subsoils thus to differ — one from the other — 
and from the surface-soil that rests upon them ? Are there 
any principles by which such differences can be accounted for — 
by which they can be foreseen — by the aid of which we can 
tell what kind of soil may be expected in this or that district, 
even without visiting the spot, and on what kind of subsoil it 
is likely to rest ? 

Geology explains the cause of many of these differences, 
and supplies us with principles by which we can predict the 
general quality of both soils and subsoils in the several parts 
of entire kingdoms ; and where the soil is of inferior quality, 
and yet susceptible of improvement, the same principles indi- 
cate whether the means of improving it are likely to exist in 
any given locality, or to be attainable at a reasonable cost. 

It will be proper shortly to illustrate these direct relations of 
geology to agriculture. 



CHAPTER YT. 

Direct relations of geology to agriculture. — Origin of soils. — Causes of their 
diversity. — Relation of soils to the rocks on which they rest. — Constancy 
in the relative position and character of the stratified rocks. — Relation ot 
this fact to practical agriculture. — Of primary, secondary, tertiary, and 
post-tertiary rocks. — Different soils observed upon each of these divisions 
along the Atlantic sea-hoard of North America. 

Geology is that branch of knowledge which embodies all 
ascertained facts in regard to the nature and internal structure, 
both physical and chemical, of the solid parts of our globe. 
This science has many close relations with practical agriculture. 
It especially throws much light on the na.ture and origin of 
soils — on the causes of their diversity — on the agricultural capa- 
bilities, absolute and comparative; of different farming districts 
and countries — on the unlike effects produced by the same 
manure on different soils — on the kind of materials, by admix- 
ture with which they may be permanently improved — and on 
the sources from which these materials may be derived. 

It tells beforehand, also, and by a mere inspection of the 
may, what is the general character of the land in this or that 
district of a country — where good land is to be expected — where 
improvements are likely to be effected — of what kind of im- 
provements this or that district will be susceptible — and where 
the intending purchaser may hope to lay out his money to the 
greatest advantage. 

SECTION I. OF THE CRUMBLIXG OF ROCKS AND THE ORIGIX OF SOILS. 

If we dig down through the soil and subsoil to a sufficient 
depth, we always come sooner or later to the solid rock. In 
many places the rock actually reaches the surface, or rises in 
4* 



82 GENERAL COMPOSITION OF ROCKS. 

cliffs, hills, or ridges, far above it. The surface (or crust) of 
our globe, therefore, consists everywhere of a more or less solid 
mass of rock, overlaid by a covering, generally thin, of loose 
materials. The upper or outer part of these loose materials 
forms the soil. 

The geologist has travelled over great part of the earth's 
surface, has examined the nature of the rocks which everywhere 
repose beneath the soil, and has found them to be very unlike in 
appearance, in hardness, and in composition — in different coun- 
tries and districts. In some places he has met with a sandstone, 
in other places a limestone, in others a slate or hardened rock 
of clay. But a careful comparison of all the kinds of rock he 
has observed has led him to the general conclusion that they are 
all either sandstones, limestones, or clays of different degrees of 
hardness, or a mixture in different proportio7is of two or more of 
these kinds of matter. 

When the loose covering of earth is removed from the sur- 
face of any of these rocks, and this surface is left exposed, sum- 
mer and winter, to the action of the winds and rains and frosts, 
it may be seen gradually to crumble away. Such is the case 
even with many of those which, on account of their greater 
hardness, are employed as building-stones, and which, in the 
walls of houses, are kept generally dry ; how much more with 
such as are less hard, or lie beneath a covering of moist earth, 
and are continually exposed to the action of water. The natural 
crumbling of a naked rock thus gradually covers it with loose 
materials, in which seeds fix themselves and vegetate, and which 
eventually form a soil. The soil thus produced partakes neces- 
sarily of the chemical character and composition of the rock on 
which it rests, and to the crumbling of which it owes its origin. 
If the rock be a sandstone, the soil is sandy — if a claystone, it 
is a more or less stiff clay- -if a limestone, it is more or less 
calcareous — and if the rock consist of any peculiar' mixture of 
those three substances, a similar mixture is observed in the 
earthy matter into which it has crumbled. 



RELATIOXS OF SOILS TO ROCKS. 83 

Led by this observation, the geologist, after comparing the 
rocks of different countries with one another compared next the 
soils of various districts with the rocks on which they immedi- 
ately rest. The a-cmral result of this comparison has been, that 
in almost every country the soils* as a whole, have a resemblance 
to the rocks beneath them, similar to that which the loose earth 
derived from the crumbling of a rock before our eyes bears to 
the rock of which it lately formed a part. The conclusion, 
therefore, is irresistible, that soils, generally speaking have been 
formed by the crumbling or decay of the solid rocks — that there 
was a time vv hen these rocks were naked and without any cover- 
ing of loose materials — and that the accumulation of soil has 
been the slow result of the natural degradation or wearino; 
away of the solid crust of the globe. 



'O' 



SECTION II. CAUSE OF THE DIVERSITY OF THE SOILS. 

The cause of the diversity of soils in different districts, there- 
fore, is no longer obscure. If the subjacent rocks in two local- 
ities differ, the soils met with there are likely to differ also, and 
in an equal degree. 

But why, it may be asked, do we find the soil in some coun- 
tries uniform in mineral'^ character and general fertility over 
hundreds or thousands of square miles, while in others it varies 
from field to field — the same farm often presenting many well- 
inarked differences both in mineral character and in agricultural 
value ? A chief cause of this is to be found in Ihe mode in 
which the different rocks are observed to lie — upon or by the 
side of each other.f 

1. Geologists distinguish rocks into two classes, the stratified 
and the unst ratified. The former are found lying over each 
other in separate beds or strata, like the leaves of a book when 

* That is, containing the same general proportions of sand, clay, lime,' &c , 
or colored red by similar quantities of oxide of iron. 

•j- For another important cause, see Section II. of Chapter YIII. 



84 



STRATIFIED AND UXSTHATIFIED ROCKS. 



kid on its side, or like the layers of stones in the wall of a 
building. The latter — the unstratified rocks — form hills, moun- 
tains, or sometimes ridges of mountains, consisting of one more 
or less solid mass of the same material, in which no layers or 
strata are usually anywhere or distinctly perceptible. Thus, in 
the following diagram, (No. 1,) A and B represent unstratified 
masses, in connection with a series of stratified deposits, 12 3, 
lying over each other in a horizontal position. On A one kind 
of soil will be formed, on C another, on B a third, and on D a 
fourth — the rocks being all different from each other. 

No. 1. 

!5 




If from A to D be a wide valley of many miles in extent, the 
undulating plain at the bottom of the valley, resting in great 
part on the same rock, (2,) will be covered by a similar soil. 
On B the soil will be different for a short space ; and again it 
will differ at the bottom of the valley C, and on the first ascent 
to A, at both of which places the rock (3) rises to the surface. 
In this case the stratified rocks lie horizontally ; and it is the 
undulating nature of the country which, bringing different kinds 
of rock to the surface, causes a necessary diversity of soil. 

2. But the degree of inclination which the beds possess is a 
more frequent cause of variation in the characters of the soil 
in the same district, and even at very short distances. This 
is shown in^the annexed diagram, (No. 2,) where ABODE 
represent the mode in which the stratified rocks of a district 
of country not unfrequently occur in connection with each 
other. 

No. 2. 




Proceeding from E in the plain, the soil would change when 



ORDER OF SUCCESSION CONSTANT. 85 

we came upon tlie rock D, but would continue pretty uniform 
in quality till we reached the layer C, Each of these layers 
may stretch over a comparatively level tract of perhaps hun- 
dreds of miles in extent. Again, on climbing the hill-side, 
another soil would present itself, which would not change till 
we arrived at B. Then, however, we begin to walk over the 
edges of a series of beds, and the soil may vary with every 
new stratum or bed we pass over, till we gain the ascent to A, 
where the beds are much thinner, and where, therefore, still 
more frequent variations may present themselves. 

Everywhere over the British islands valleys are hollowed 
out, as in the former of these diagrams, (No. 1,) by which the 
different rocks beneath are in different places exposed and dif- 
ferences of soil produced ; or the beds are more or less inclined, 
as in the latter diagram, (No. 2,) causing still more frequent 
variations of the land to appear. By a reference to these facts, 
therefore, many of the greater diversities which the soils of the 
country present may be satisfactorily accounted for. 

SECTION III. OF THE CONSTANCY IN MINERAL CHARACTER, AND 

ORDER OF SUCCESSION, WHICH EXISTS AMONG TPIE STRATIFIED 
ROCKS. 

Another fact, alike important to agriculture and to geology, 
is the natural order or mode of arrangement in which the stra- 
tified rocks are observed to occur in the crust of the globe. 
Thus, if 1 2 3 in diagram No. 1 represent three different kinds 
of rock — a limestone, for example, a sandstone, and a hard clay 
rock (a shale or slate) lying over each other in the order here 
represented — then, in whatever part of the country, nay, in 
whatever part of the v/orld these same rocks are met with, 
they will always be found in the same position. The bed 2 or 
3 will never he observed to lie over the bed 1. 

This fact is important to geology, because it enables this 
science to arrange all the stratified rocks in a certain invariable 



86 DEDUCTIONS FROM THIS. 

order — wliicli order indicates their relative age or antiquity — 
since that rock which is lowest, like the lowest layer of stones 
in the wall of a building, must generally have been the first 
deposited, or must be the oldest. It also enables the geologist 
on observing the kind of rock which forms the surface in any 
country, to predict at once whether certain other rocks are 
likely to be met with in that country or not. Thus at C, 
(diagram No. 1,) where the rock 3 comes to the surface, he 
knows it would be in vain, either by sinking or otherwise, to 
seek for the rock 1, the natural place of which is far above it ; 
while, at D, he knows that by sinking he is likely to find either 
2 or 3, if it be worth his while to seek for them. 

To the agriculturist this fact is important, among other 
reasons, — 

1. Because it enables him to predict whether certain kinds 
of rock, which may be used with advantage in improving his 
soil, are likely to be met with within a reasonable distance or 
at an accessible depth. Thus, if the bed D (diagram No. 2) 
be a limestone, the instructed farmer at E knows that it is not 
to be found by sinking into his own land, and therefore brings 
it from D ; while to the farmer upon C it may be less expen- 
sive to dig down to the bed D in one of his own fields, than to 
cart it from a distant spot, where it occurs on the surface. 
Or, if the farmer requires clay, or marl, or sand, to ameliorate 
his soil, this knowledge of the constant relative position of beds 
enables him to say where these materials are to be got, or 
where they are to be looked for, and whether the advantage to 
be derived is likely to repay the cost of procuring them. 

2. It is observed that, when the soil on the sur^ce of eadi 
of a series of rocks, such as C or D or E, (diagram No. 2,) is 
uniformly bad, it is almost umformly of letter quality at the 
point where the tioo rocks meet. Thus C may be dry, sandy, and 
barren ; D may be a cold unproductive clay ; and E a more 
or less unfruitful limestone soil ; yet at either extremity of the 
tract D, where the soil is made up of an admixture of the 



PRACTICAL YALUE OF GEOLOGICAL KNOWLEDGE. 81 

decayed portions of the two adjacent rocks, the land may be 
of average fertility — the sand of C may adapt the adjacent 
clay to the growth of turnips, while the lime of E may cause it 
to yield large returns of wheat.* Thus, to the tenant in look- 
ing out for a farm, or to the capitalist in seeking an eligible 
investment, a knowledge of the mutual relations of geology 
and agriculture will often prove of the greatest assistance. 
But how little is such really useful knowledge diffused among 
either class of men — how little have either tenants or proprie- 
tors been hitherto guided by it in their choice of the local- 
ities in which they desire to live ! 

3. The further fact that the several stratified rocks are re- 
markably constant in their general mineral character, renders 
this knowledge of the order of relative superposition still more 
valuable to the agriculturist. Thousands of different beds 
are known to geologists to occur on various parts of the earth's 
surface — each occupying its own unvarying place in the series. 
Most of these beds also, when they crumble or are worn down, 
produce soils possessed of some peculiarity by which their 
general agricultural capabilities are more or less affected, — and* 
these peculiarities may gcnercdly be observed in soils formed 
from rocks of the same age — that is, occupying the same place 
in the series — in whatever part of the world we find them. 
Hence, if the agricultural geologist be informed that his friend 
has bought, or is in treaty for a farm or an estate, and that it 
is situated upon such and such a rock, or geological formation, 
or is in the immediate neighborhood of such another,- — he can 
immediately give a very probable opinion in regard to the 
agricultural value of the soil, whether the property be in Eng- 
land, Australia, or in New Zealand. If he knows the nature 
of the climate also, he will be able to estimate with tolerable 
correctness how far the soil is likely to repay the labors of 
the practical farmer — nay, even whether it is likely to suit 
better for arable land or for pasture ; and if for arable, what 

* See p. 84. 



88 AGRICULTURAL VALUE OF GEOLOGY. 

species of grain and root crops may be expected to produce 
most abundantly. 

These facts are so very curious, and illustrate so beautifully 
the value of geological knowledge — if not to A and B, the holders 
and proprietors of this and that small farm, yet to enlightened 
agriculturists, to scientific agriculture in general — that I shall 
explain this part of the subject more fully in a separate section. 
To those who are now embarking in such numbers in quest of 
new homes in our numerous colonies — who hope to find, if not a 
more willing, at least a more attainable soil in new countries — 
no kind of agricultural knowledge can at the outset, — I may 
say, even through life — be so valuable as that to v.-hich the rudi- 
ments of geology will lead them. Those who prepare themselves 
the best for becoming farmers or proprietors in Canada, in 
New Zealand, or in wide Australia, leave their native land in 
general without a particle of that preliminary practical know- 
ledge which would qualiTy them to say, when they reach the 
land of their adoption, " on this spot rather than oh that 
— in this district, rather than that, — will I purchase my 
allotment, because though both appear equally inviting, yet 
I know, from the geological structure of the country, that 
here I shall have the more permanently productive soil ; 
here I am more within reach of the means of agricultural im- 
provement; h'fere, in addition to the riches of the surface, my 
descendants may hope to derive the means of wealth from mine- 
ral riches beneath." And this oversight has arisen chiefly from 
the value of such knowledge not being understood — often from 
the very nature of it being unknown, even to otherwise well- 
instructed practical men. It is not to men well skilled merely 
in the details of local farming, and who are therefore deservedly 
considered as authorities, and good teachers in regard to local 
or district practice, that we are to look for an exposition, often 
not even for a correct appreciation of those general principles 
on which a universal system of agriculture must be based — 
without which, indeed, it must ever remain a mere collection of 



SUBDIVISIONS jOF STRATIFIED ROCKS. 89 

empirical rules, to be studied and laboriously mastered in every 
new district we go to — as the traveller in foreign lands must 
acquire a new language every successive frontier he passes. 
England, the mistress of so many wide and unpeopled lands, 
over which the dwellings of her adventurous sons are hereafter 
to be scattered, on which their toil is to be expended, and the 
glory of their motherland by their exertions to be perpetuated — 
England should especially encourage all such learning, and the 
sons of English farmers should willingly avail themselves of 
every opportunity of acquiring it. 

• 

SECTION IV. OF THE SUBDIVISIONS OF THE STRATIFIED ROCKS, 

AND OF OBSERVED DIFFERENCES AMONG THE SOILS THAT RESt 
UPON THEil. 

The thousands of beds or strata of which I have spoken as 
lying one over the other in the crust of the globe, have — partly 
for convenience, and partly in consequence of certain remarkably 
distinctive characters observed among them — been separated by 
geologists into thre« great divisions. The primary are the 
lowest and the oldest ; the secondary lie over these ; and the terti- 
ary are the uppermost, and have been most recently formed. The 
sands, gravels, clays, and alluvial deposits, which in many places 
overlie the solid rocks and the beds of soft limestone, in many 
places formed by calcareous springs, are often spoken of as post- 
tertiary. 

In some countries, on the surface of which these several 
divisions of the strata are seen to succeed each other very closely, 
the character of the surface soil and its agricultural capability 
are also seen to vary as we pass from the rocks of the one epoch 
to those of the other. This is the case, for example, in the more 
southernly of the United States of America which lie along the 
Atlantic border. As we walk inland from the sea-shore, we 
pass over low and swampy, but rich muddy flats, which yield 
large returns of sea-island cotton and rice. As we proceed, the 



90 DIFFERENT ROCKS OF THE 

ground gradually rises above the sea-level — becomes firmer and 
drier — and instead of the swamp willow and cypress, bears the 
hickory and the oak. Tobacco and sugar are the marketable 
crops on this drier land, and Indian corn tlie staple food of the 
colored population. After twenty miles or so, the edge of this 
drier alluvial plain is reached, and we ascend a low escarpment 
or terrace of yellow sand. Here we find ourselves amid thin 
forests of unmixed natural pine, growing upon a poor sandy 
soil ; and till v/e cross this belt and reach a second terrace, few 
corn-fields, or attempts at clearing for the purposes of cultiva- 
tion meet the eye. The new terrace presents the remarkable 
contrast of an open prairie, void of trees, covered with a thin 
Soil waving with grass, and resting, like our English downs, on 
chalk rocks beneath. This tract is dry and deficient in water; 
but the thin soil, when turned over, yields crops of corn, and 
bears, among others, a variety of hard wheat, known in the 
market by the name of Georgian wheat. Still farther on this 
prairie is passed, and we ascend hilly slopes, upon wiiich clays 
and loams of various qualities and capabilities occur at intervals 
intermingled, and broad-leaved trees of various kinds ornament 
the landscape. It is a country fitted for general husbandry, 
propitious to skill and industry, and, by its climate, adapted to 
the constitution of settlers of European blood. 

These changes in agricultural character and capability are 
coincident with changes in the geological age of the beds which 
form its surface. This I have shown in the following section of 
the coast-line in question, from the sea to the mountains. The 
letterpress below the section indicates the geological formiations ; 
that placed above it indicates, first, the natural vegetation, and 
then the kind of husbandry and of labor v/hich are best adapted 
to each. 



AMERICAN ATLANTIC BORDER. 



91 



Broad-loaved forests. 
General husbandry. 



No. 3. 
Oak 
Swamp and 
willow, hickory. 

Dry chalk downs. "White labor. 

Rice Sugar Pine forests. Treeless prairies. * 

and and Sandy barrens. ■ 

cotton, tobacco. Georgian wheat 



Little cultivation. 




Colored labor 



Sea. Post-tertiary, 
and alluvial. 



Tertiary sands. Secondary Primary metamorphic* 
chalk marks. rocks and granite. 



In this section the reader will observe a close general relation 
between the changes in geological and agricultural character 
which appear on the several successive terraces or flats of laud 
which intervene between the shores of the Atlantic and the slopes 
of the Alleghany Mountains. Where the most recent or alluvial 
loams and rich clays end, there the tobacco, Indian corn, and even 
wheat culture, for the time, end also. The tertiary sands be- 
long to a more ancient epoch, and to them are limited, by a 
strictly defined boundary on each side, the dark pine forests 
which are so striking a feature of the country. On the still 
older chalk, again, the treeless prairie and flinty wheat country 
is as distinctly limited by the formations on either hand; and 
beyond this, again, the changed forests and cultivation of the 
higher country are determined by the change in nature and in 
age which the rocks of this region exhibit. 



* The word metamorphic here used means changed or altered — ^as clay, 
for example, is changed when it is baked into tiles or bricks. 



CHAPTER YII. 

Subdivisions of the tertiary, secondary, and primary groups of rocks. — 
Agricultural relations of the crag and London clay. — Fossil phosphates 
of the crag; quantity and value of these. — Soils of the London and 
plastic clays. — Of the chalk and green-sand. — Ware malt. — Clays of 
the "Weald and Lias. — Rich soils of the new red sandstone. — Contrast 
between those of the millstone grit and mountain limestone. — Soils of the 
Silurian, Cambrian, and Mica slate rocks. General conclusions as to the 
relations of geology to agriculture. 

But tlie several great groups of strata, of which we h'ave 
spoken under the names of primary, secondary, &c., are them- 
selves broken up or subdivided by geologists into a variety of 
subdivisions called systems and formations, each of which pos- 
sesses its peculiar mineral characters and special agricultural 
relations. These, in so far as relates to the geology of our own 
country, it will be proper briefly to indicate. 

SECTION I. THE TERTIARY STRATA. 

The tertiary strata, as they occur in England, consist chiefly 
of the crag, which lies above, and the Loudon and plastic clays, 
which follow each other underneath. 

1. The Crag consists of a mass of rolled pebbles mixed with 
marine shells and corals, and resting upon beds of sand and 
marl. It is in places as much as 50 feet in thickness, though 
generally of less depth, and forms a strip of flat land, a few 
miles in width, along the eastern shores of Norfolk and Suffolk. 
The soil is generally fertile, but varies in value from 5s. to 25s. 
an acre of rent. 

This crag Ls chiefly interesting to the agriculturist from its 



NODULES OF PHOSPHATE OF LIME. 93 

containing hard, rounded, flinty nodules — often spoken of as 
coprolitcs — in which as much as 50 per cent of phosphate of lime 
(bone-earth) is frequently found. These nodules are scattered 
through the body of the marls, and through the subsoils of the 
fields far inland, and are collected for sale to the manufacturers 
of super-phosphate of lime and other artificial manures. Some 
parties are said to have dug up as much as 60 or tO tons a-week.* 

2. The London and j)lastic clays, from 500 to 900 feet thick, 
consist of stiff, almost impervious, dark-colored clays — the soils 
formed from which are still chiefly in pasture. The lower beds — 
the plastic clay — are mixed with sand, and produce an arable 
soil ; but extensive heaths and wastes rest upon them in Berk- 
shire, Hampshire, and Dorset. The crops of corn and roots 
yielded by the stiff clay soils of these strata have hitherto, in 
many districts, been found insufficieilt to pay the cost of raising 
them. The drain and the subsoil plough, with lime or chalk — ■ 
in which these clays are very deficient, and for the addition ol 
which they are very grateful — would render them more produc- 
tive and more profitable to the farmer. 

SECTION II. THE SECONDARY STRATA. 

3. The Chalk, about 600 feet in thickness, lies below the Lon- 
don and plastic clays above described. It consists — as shown 
in the section No. 4 — in the upper part, of a purer chalk with 



* The cost of digging up, screening, cleaning, &c., of these nodules, is 
about 5s. a ton, and they are delivered on board the vessel at 30s. to 45s. 
The quantity of the fossils which is scattered over this part of the county, 
and the treasure they are now proving to the owners of the land, may be 
judged of from two facts stated by Mr. Herapath, {Jour. Royal Agric. Soc, 
xii. p. 93,) "that £60, £70, and £80, have been repeatedly given for leave 
to dig over a two-acre field;" and "that the land itself is actually improved 
by the course of treatment to which it is subjected when excavating for the 
fossils. 



94 



THE CHALK AXD GREEN-SAND. 



Suffolk. 



No. 4. 

Mouth of the Thames. Kent. 




1. London clay. 

2. Plastic clay. 



3. Upper chalk, with flints. 

4. Under chalk, without flints. 



layers of flint, (3) ; in the lower, of a marly chalk without 
flints, (4.) The soil of the upper chalk is chiefly in sheep- 
walks ; that of the lower chalk is very productive of corn. In 
some localities, (Croydon,) the arable soils of the upper chalk 
have lately been rendered much more productive in corn and 
beans by deep ploughing, and thus mixing with the upper soil as 
much as 6 or 8 inches of the inferior chalk. Excellent crops of 
carrots also have been obtained by deep-forking such land. 

The general and comparative agricultural value of the soils 
upon the chalk may, to a certant extent, be judged of by the 
fact, that, in the lowest-rented counties in England, chalk is the 
prevailing rock. 

4. The Green-sand, 500 feet thick, consists of 150 feet of 
clay, with about 100 feet of a greenish, more or less indurated, 
sand above, and 250 feet of sand or sandstone below it. The 
upper sand forms a very productive arable soil ; but the clay 
forms impervious wet and cold lands, chiefly in pasture. The 
lower sand is generally unproductive. 

In the green-sand, both upper and lower, but especially in the 
upper, beds of marl occur, in which are found layers of so-called 
coprolites and other organic remains, rich in phosphate of lime. 
To the presence of these beds is ascribed the fertility of the 
soil of the upper green-sand, which in some localities is very 
remarkable, and, as at Farnham in Surrey, is found to be espe- 
cially favorable to the growth of hops. The organic remains are 
in some places so abundant, that, as in the crag, they are sought 



FERTILITY OF MIXED SOILS. 95 

for and dug up, as a natural source of the phosphate of lime, 
usually supplied to the soil directly in the form of bones. 

It is an important agricultural remark, that where the plastic 
clay comes in contact with the top of the chalk, an improved 
soil is produced ; and that where the chalk and the green-sand 
mix, extremely fertile patches of country present themselves. 

The following imaginary section shows the relative positions 
of these two fertile strips of country, above and below the chalk. 

At the contact with the plastic clay it is particularly adapted 
for the growth of barley, which, for quality and malting proper- 
ties, is not excelled by any in the kingdom. In Essex, barley 
grown on this soil is principally sold to maltsters at Stortford, 
&c. ; and when malted, is sold again in London under the name 
of Ware malt. This name is derived from Ware in Hertford- 
shire, a market town standing on a similar soil. 

No. 5. 
"Wheat and hop land. Barley soils. 




.plastic Clay: 
Green- Sand. "'•--^^ Chalk. 

The soils at the contact of the chalk and upper green-sand 
are celebrated for their crops of wheat, in producing which the 
phosphates in the marls of the upper green-sand are supposed to 
have some infxuence, 

5. The Weolden formation, which succeeds the green-sand, is 
nearly 1000 feet thick, and consists of 400 feet of sand, covered 
by 300 of clay, resting upon 250 of marls and limestones. 
The clay forms the poor, wet, but improvable pastures of Sus- 
sex and Kent. These clays, in many places, harden like a 
brick when dried in the air ; and clods which have lain long in 
the sun, ring, when struck, like a piece of pottery. By drain- 
ing alone, their produce has been raised from 16 to 40 bushels 
of wheat an acre. On the sands below the clay rest heaths 
and brushwood ; but where the marls and limestones come to 



96 THE WEALDEN AND OXFORD CLAYS. 

the surface, the land is of better quality, and is susceptible of 
profitable arable culture. 

6. In the U^per oolite, of 600 feet in thickness, we have a 
bed of clay (Kimmeridge clay) 50D feet thick, covered by 100 
feet of sandy limestones. The clay lands of this formation are 
difficult and expensive to vrork, and are therefore chiefly in old 
pasture. The sandy limestone soils above the clay are also 
poor ; but where they rest immediately upon, and are inter- 
mixed with, the clay, excellent arable land is produced. 

7. The Middle oolite, of 500 feet, consists also of a clay, 
(Oxford clay,) dark blue, adhesive, often rich in lime, and 
nearly 400 feet thick, covered by 100 feet of limestones and 
sandstones. These latter produce good arable land where the 
lime happens to abound, but the clays, especially while un- 

, drained, form close heavy compact soils, most difiBcult and ex- 
pensive to work. In wet weather they are often adhesive like 
bird-lime, and in dry summers become hard like stone, so as to 
require a pick-axe to break them. They have therefore hitherto . 
been very partially brought into arable culture. . The extensive 
pasture-lands of Bedford, Huntingdon, Northampton, liincoln, 
Wilts, Oxford, and Gloucester, rest chiefly upon this clay ; as 
do also the fenny tracts of Lincoln and Cambridge. ^The use 
of burned clay upon the arable land has, in some parts of this 
clay district, been of much advantage, 

8. The Lower or Bath oolite, of 500 feet in thickness, con- 
sists of many beds of limestone and sandstone, with about 200 
feet of clay in the centre of the formation. The soils are very 
various in quality, according as the sandstone or limestone pre- 
dominates in each locality. The clays are chiefly in pasture : 
the rest is more or less productive, easily worked, arable land. 
In Gloucester, Northampton, Oxford, the east of Leicester, 
and in Yorkshire, this formation is found to lie immediately 
beneath the surface, and a little patch of it occurs also on the 
south-eastern coast of Sutherland. 

9. The Lias is an immense deposit of blue clay, from 500 to 



THE COAL MEASURES. 97 

1000 feet in thickness, wliicli produces cold, blue, unproductive 
clay soils. It forms a long stripe of land, of varying breadth, 
which extends, in a south-western direction, from the mouth of 
the Tees, in Yorkshire, to Lyme Regis, in Dorset. It is chiefly 
in old, and often very valuable pasture. An efficient system of 
drainage will by-and-by convert much of this clay into most 
productive wheat land. 

10. The New red sandstone, though only 500 feet in thickness, 
forms the surface of nearly the whole central plain of Eng- 
land, and stretches northwards through Cheshire to Carlisle 
and. Dumfries. It consists of red sandstones and red marls, 
the soils produced from which are easily and cheaply worked, 
and form some of the richest and most productive arable lands 
in the island. This is in some degree indicated by the fact that 
the three highest-rented counties in England rest chiefly upon 
this rock. In whatever part of the world the red soils of this 
formation have been met with, they have been found to possess 
in general the same valuable agricultural capabilities, 

11. The Mag7iesian limestone, from 100 to 500 feet in thick- 
ness, is covered by a stripe of generally poor thin soil, extend- 
ing from Durham to Nottingham, capable of improvement as 
arable land by high farming, but bearing naturally a poor pas- 
ture, intermingled with sometimes magnificent furze. 

12. The Coal measures, from 300 to 3000 feet thick, consist 
of beds of grey safndstone, and of dark blue shale, or har- 
dened clay, intermingled {inter-stratified) with beds of coal. 
Where the sandstones come to the surface, the soil is thin, poor, 
hungry, sometimes almost worthless. The shales, on the other 
hand, produce stiff, wet, almost unmanageable Mays — not un- 
workable, yet expensive to work, and requiring draining, lime, 
skill, capital, and a zeal for improvement to be applied to them, 
before they can be made to yield the remunerating crops of 
corn they are capable of producing. The blaes or shales of 
this formation, when dug out of cliffs or brought from coal- 
mines, may be laid with advantage on loose sandy soils, and 

5 



98 



MILLSTONE GRIT. 



600 feet or upwards in thick- 
It lies below the coal, but is 
sandstones and shales of the 



even, it is said, on the stiff whitish clays almost destitute of 
vegetable matter, which, as in Lanarkshire, occasionally occur 
on the surface of our coal-fields. 

13. To the Millstone grit, of 
ness, the same remarks apply, 
often only a repetition of the 
coal measures, and forms in many cases soils still more worth- 
less. Where the sandstones prevail, large tracts lie naked, or 
bear a thin and stunted heath. Where the shales abound, the 
naturally difficult ^soils of the coal shales again recur. The 
rocks of this formation generally approach the surface, around 
the outskirts of our coal-fields. 

This arises from the circumstance that our coal measures 
often lie in basin-shaped deposits, from beneath each edge of 
which, the millstone grit and mountain limestone rocks rise up 
to the surface. This is illustrated by the annexed section, (No. 
6,) across a part of Lancashire, in which 1 represents the coal 
measures ; 2 the coarse sandstones, &c. of the millstone grit ; 
3 a thick shale-bed, which often overlies the thick masses of 
mountain limestone represented by 4. 



Boulsworth hill. 
1689. 




The traveller passes off the poor, often cold and wet, clay 
soils of the coal measures, on to the equally poor lands of 
the millstone grit, and over its top, as at Pendle hill, descends 
upon the sweet herbage and rich dairy pastures of the moun- 
tain limestone at 4. 

The section shows also how in this country the millstone grit 



OLD RED SANDSTONE SOILS. 99 

often rises into high hills. These are then covered with poor 
heaths and worthless moors, while limestone hills of equal 
height bear green herbage to the very top. 

14. The Mountain limestone, 800 to 1000 feet thick, is a hard 
blue limestone rock, separated here and there into distinct beds 
by layers of sandstones, of s"andy slates, or of bluish-])lack 
shales like those of the coal measures. The soil upon the 
limestone is generally thin, but produces a naturally sweet 
herbage, everywhere superior in value to that which grows on 
the sandier soils of the millstone grit. When the limestone 
and clay (shale) adjoin each other, as where 3 and 4 in the 
section meet, arable land occurs, which is naturally productive 
of oats, and where the climate is favourable, may, by skilful 
treatment, be converted into good wheat land. In the north 
of England — in Derbyshire, for example, and among the York- 
shire dales — a considerable tract of country is covered by 
these rocks ; but in Ireland they form nearly the whole of the 
interior of the island. 

15. The Old red sandstone varies in thickness from 500 to 
10,000 feet. It possesses many of the valuable agricultural 
qualities of the new red,, (No. 10,) consisting, like it, of red 
sandstones and red marls, which -crumble down into rich red 
soils. Such are the soils of Brecknock, Hereford, and part of 
Monmouth ; of part of Berwick and Roxburgh ; of Hadding- 
ton and Lanark ; of southern Perth ; of either shore of the 
Moray Firth ; and of part of Sutherland, Caithness, and the 
Orkney islands. In Ireland, also, these rocks abound in Tyrone, 
Fermanah, and Monahan ; in Waterford, in Mayo, and in 
Tipperary. In all these, places the soils they form are generally 
the best in their several neighborhoods. Here and there, 
however, where the sandstones are harder, more silicious and 
impervious to water, tracts, sometimes extensive, of heath and 
bog occur ; while in others the rocks have crumbled into hun- 
gry sands, which swallow up the manure, and are expensive to 
maintain in arable culture. 



100 THE PRIMARY STRATA 



SECTION III. THE PRIMARY STRATA. 

The primary stratified rocks, which lie underneath all those 
already described, are separable into three natural divisions ; 
the Silurian'^ above, which contain the remains of animals in 
a fossil state ; the Cambrian^ below, in which no animal 
remains have yet been discovered ; and, lowest of all, the 
mica slate and gneiss rocks, which exhibit marks of change or 
alteration by tlie agency of heat. Hence these last are ofteu 
spoken of as metamoi-'phic, or changed rocks. 

16. The Upper Silurian system is nearly 4000 feet m thick- 
ness, and forms the soils which cover the lower border counties 
of Wales. It consists of sandstones and shales, with occasional 
limestones ; but the soils formed from these beds take their 
character from the general abundance of the clay. They are 
cold — ^^usually unmanageable muddy clays ; with the remarkably 
inferior agricultural value of which the traveller is immediately 
struck, as he passes westward from the red sandstones of 
Hereford to the Upper Silurian rocks of the county of Radnor. 

It. The Loiver Silurian rocks are many thousand feet in 
thickness, and in Wales lie to the west and north of the Upper 
Silurian rocks. They consist, on the upper part, of about 
25,000 feet of sandstone, on which, when the surface is not 
naked, barren heaths alone rest. 

Beneath these sandstones lie 1200 feet of sandy and earthy 
limestones, from the decay of which, as may be seen on the 
soutliern edge of Caermarthen, fertile arable lands are produced. 

The high land, which stretches across the whole of southern 
Scotland, from St. Abb's head to Portpatrick, including the 
Lammermuir hills, so far as they have yet been examined, con- 
sists of strata belonging to the upper part of the Lower Silu- 
rian, and the lower part of the Upper Silurian. The soils in 

* Or older Falaiozoic, as containing evidences of most ancient life. 
f Or Azoic, from containing no traces of life. 



CAMBRIAN SYSTEM, MICA SLATE, AND GNEISS. 101 

general are of inferior quality, the slaty rocks crumbling with 
difficulty, and being poor in lime. Cold and infertile farms 
cover the higher grounds, and wide heathy moors and bogs. 

18. The Cambrian system — meaning by this term unaltered 
rocks, containing no fossils — is at present a subject of dispute 
among geologists, and its limits even in our own island are not 
well defined. It is probably many thousand feet in thickness — 
lies beneath the Lower Silurian — and in its agricultural re- 
lations has much resemblance to these rocks. It consists in 
great part of slaty rocks, more or less hard, which often crum- 
ble very slowly, and almost always produce either poor and 
thin soils — or cold, difficultly manageable clays, expensive to 
work, and requiring high farming to bring them into profitable 
arable cultivation. In Cornwall, western Wales, the mountains 
of Cumberland ; in the mountains of Tippejary, in the extreme 
south of Ireland, on its east coast, and far inland from the bay 
of Dundalk, such slaty rocks occur, though the limits of the 
two formations have not been everywhere defined. Patches of 
rich, well-cultivated land occur here and there in these districts, 
with much also that is improvable ; but the greater part is 
usurped by worthless heaths and extensive bogs. On the dif- 
ficult soils of those formations — thinly peopled, inhabited by 
small farmers with little capital^ and therefore hitherto neglected 
• — much improvement is now here and there appearing ; and 
the introduction of the drain promises to make much corn 
grow, where little food, either for man or beast, was previously 
produced. These rocks in general contain little lime, and 
therefore, after the drain, the addition of lime is usually one of 
the most certain means of increasing the productiveness of the 
soils formed from them. 

19. The Mica • slate and Gneiss systems are of unknown 
thickness, and consist chiefly of hard and slaty rocks, crumb- 
ling slowly, forming poor, thin soils, which rest on an imper- 
vious rock, and which, from the height to which this formation 
generally rises above the level of the sea, are rendered more 



102 GENERAL CONCLUSIONS. 

unproductive by an unpropitious climate. They form extensive 
heathy tracts in Perth and Argyle, and on the north and west 
of Ireland. Here and there only — in the valleys or sheltered 
slopes, and by the margins of the lakes — spots of bright green 
meet the eye, and patches of a willing soil, fertile in corn. 

SECTION IV. GENERAL CONCLUSIONS AS TO THE RELATIONS OF 

GEOLOGY TO AGRICULTURE. 

A careful perusal of the preceding sketch of the general 
agricultural capabiUties of the soils formed from the several 
classes of stratified rocks, will have presented to the reader 
many illustrations of the facts stated in the previous chapter. 
He will have drawn for himself — to specify a few examples — 
the following among other conclusions : — 

1. That some formations, like the new red sandstone, yield 
a soil almost always productive ; others, as the coal measures 
and millstone grits, a soil almost always naturally itnproduct- 
ive ; and others, again, like the mountain limestones, a short 
sweet herbage, grateful to cattle, and productive of butter 
and cheese. 

2. That good — or better land, at least, than generally pre- 
vails in a district — may be expected where +wo formations, or 
two different kinds of rock, meet. As when a limestone and 
a clay mingle their mutual ruins for the formation of a com- 
mon soil.* 

3. That in almost every country extensive tracts of land, on 
certain formations, will be found laid down to natural grass, in 
consequence of the original difficulty and expense of working. Such 
are the Lias, the Oxford, the Weald, the Kimmeridge, and the 
London clays. In raising corn, it is natural that the lands 
which are easiest and cheapest worked should be first sub- 
jected to the plough. It is not till implements are improved, 
skill increased, capital accumulated, and population presses, that 

* See diagram No. 5, p. 95. 



ROTATIONS OFTEN PRESCRIBED BY THE SOIL. 103 

the heavier lands in a country are rescued from perennial grass, 
and made to produce that greatly increased amount of food for 
both man and beast, which they are easily capable of yielding. 

4. That the rotations adopted in a district, though faulty, 
and, in the eyes of improved agriculture, deserving of condem- 
nation, are often not only determined, but rendered necessary 
by the natm'al structure of the country. When cold clays re- 
fuse to bear even average crops of any other kinds than wheat 
and beans, the old European rotation of wheat, beans, fallow — 
which in this country has prevailed, in many places, since the 
times of the ancient Britons — becomes almost a necessity to the 
farmer. It is unfair to blame his rotations, or accuse him of 
prejudice and ignoranc.e in clinging to them, till the natural 
condition of the land has been altered by art, so as to fit it for 
the profitable growth of other crops. 

The turnip and barley soils of Great Britain are in many dis- 
tricts, it may be, but indifferently farmed; and the State has 
reason to complain of much individual neglect* of known and 
certain methods of increasing their productiveness. But the 
great achievement which British agriculture has now to effect, is to 
subdue the stuhhorn clays, and to convert them into, what many of 
them are yet destined to become, the richest corn and grecn-crojp bear- 
ing lands in the kingdom. 

5. That there are larger tracts of country still — such as rest 
on the slates of the Lower Silurian and Cambrian systems, for 
example — from which the efforts of the enlightened agriculturist 
have hitherto been withheld, in consequence of the apparent 
hopelessness of ever bringing them into profitable culture. Over 
these tracts, however, there are large portions which will pay 
well for skilful improvement. Make roads and drains, bring in 
lime, and manure well. You will thus improve the soil, gradu- 
ally ameliorate the climate, make modern skill and improvements 
available, obtain a remunerating return for labor economically 
expended, and for capital judiciously invested, and you will at the 
same time increase the power and the resources of the country. 



CHAPTER YIII. 

Poor soils of the granites and fertile soils of the trap rocks, and of the modem 
lavas. — Composition of felspar and hornblende. — Accumulations of trans- 
ported sands, gravels, and clays. — Their influence on agricultural capa- 
bility. — Illustration from the neighborhood of Durham. — Importance of 
surface or drift geology to agriculture. — General uniformity in the agri- 
cultural character of the rocks and soils on geological formations of the 
same age. — Exceptions among the Silurian rocks. — Use of geological maps 
in reference to agriculture. 

It was stated in a preceding chapter that rocks are divided 
by geologists into the stratified and the unstratijied.^ The stra- 
tified rocks cover by far the largest portion of the globe, and 
form the great fariety of soils, of which a general description 
has just been given. The nnstratified rocks are of two kinds — • 
the granites and the trap rocks ; and as a considerable portion 
of the area, especially of the northern half, of our island is covered 
by them, it will be proper shortly to consider the peculiar char- 
acters of each, and the diiferences of the soils produced from them. 

SECTION I. POOR SOILS OF THE GRANITES, AND FERTILE SOILS OF 

THE TRAP ROCKS AND MODERN LAVAS. 

1. The Ch-anites consist of a mixture, in different proportions, 
of three minerals, known by the names of quartz, felspar, and 
mica. The latter, however, is generally present in such small 
quantity, that in our general description it may be safely left 

* The nnstratified are often called crystalline rocks, because they fre- 
quently have a glassy appearance, or contain regular crystals of certain 
mineral substances ; often also igneoiis rocks, because they appear all to have 
been originally in a melted state, or to have been produced by fire. 



POOR GRANITE SOILS. 105 

out of view. Granites, therefore, consist chiefly of quartz and 
felspar, in proportions which vary very much; but the former, 
on an average, constitutes perhaps from one-third to one-half of 
the whole. 

Quartz has already been described as being the same sub- 
stance as flint, or the silica of the chemist. When the granite 
decays, this portion of it forms a more or less coarse silicious 
sand. 

Fdsjpar is a white, greenish, or flesh-colored mineral, often 
more or less earthy in its appearance, but generally hard and 
brittle, and sometimes glassy. It is scratched by quartz, and 
thus is readily distinguished from it. When felspar decays, it 
forms an exceedingly fine tenacious clay, (pipe-clay.) 

Granite generally forms hills, and sometimes entire ridges of 
mountains. When it decays, the rains and streams wash out 
the fine felspar clay, and carry it down into the valleys, leaving 
the quartz sand on the sides of the hills. Hence the soil in the 
bottoms and flats of granite countries consists of a cold, stiff, 
wet, more or less impervious clay, which, though capable of 
much improvement by draining, often" bears only heath, bog, or 
a poor and un-nutritive pasture. The hill sides are either bare, 
or are covered with a thin, sandy, and ungrateful soil, of which 
little can be made without the application of much skill and 
industry. Yet the opposite sides of the same mountains often 
present a remarkable difference in this respect; those which are 
most beaten by the rains having the light clay most thoroughly 
washed from their surfaces, and being therefore the most sandy 
and barren. 

2. The T'rajp rocks, comprising the green-stones and basalts — 
both sometimes called whin-?>iowQ& — consist essentially* of felspar 
and hornblende or augite. In contrasting the trap rocks with 
the granites, it may be stated generally, that while the granites 

* The reader is referred for more precise information to the Author's 
"Lectures," 2d edition. 

5* 



106 



COMPOSITION OF FELSPAR AND HORNBLENDE. 



consist of felspar and quartz, the traps consist of felspar and 
hornblende (or augite.) In the traps, both the felspar and the 
hornblende are reduced, by the action of the weather, to a more 
or less fine powder, affording materials for a soil ; in the granites, 
the felspar is the principal source of the fine earthy matter they 
are capable of yielding. If we compare together, therefore, the 
chemical composition of the two minerals, (hornblende and fel- 
spar,) we shall see in what respect these two varieties of soil 
ought principally to differ. Thus they consist respectively of — 





Felspar. 


Hornblende. 


Silica, 


65 


42 


Alumina, 


18 


14 


Potash and soda, 


1*7 


trace. 


Lime, ... 


trace. 


12 


Magnesia, 


do. 


14 


Oxide of iron, 


do. 


14i 


Oxide of manganese, 


do. 


k 



100 



91 



A remarkable difference appears thus to exist, in chemical 
composition, between these two minerals — a difference which 
must affect also the soils produced from them. A granite soil, in 
addition to the silicious sand, will consist chiefly of silica, alu- 
mina, and potash, derived from the felspar, A trap soil, in addi- 
tion to the silica, alumina, and potash from its felsj)ar, will 
generally contain also much lime, magnesia, and oxide of iron, 
derived from its hornblende. If the variety of trap consist 
chiefly of hornblende, as is sometimes the case, the soil formed 
from it will derive nearly 2i- cwt. each of lime, magnesia, and 
oxide of iron, from every ton of decayed rock. A hornblende 
soil, therefore, contains a greater number of those inorganic 
substances which plants require for their healthy sustenance, and, 
therefore, will prove more generally productive than a soil of 
decayed felspar. But when the two minerals, hornblende and 
felspar, are mixed together, as they are in the variety of trap 
called green-stone, the soil formed from them must be still more 



FERTILITY OF TRAP AND GREEN-STONE SOILS. 107 

favorable to vegetable life. The potash and soda, of which the 
horubleiide is nearly destitute, is abundantly supplied by the fel- 
spar ; while the hornl)lende yields lime and magnesia, which are 
known to exercise a remarkable influence on the progress of 
vegetation. 

This chemical knowledge of the nature and differences of .the 
rocks from which, the granite and trap soils are derived, explains 
several interesting practical observations. Thus it shows — 

a. That while granite soils, in their natural state, may be 
eminently unfruitful, trap soils may be eminently fertile ; and 
such is actually the result of observation and experience in 
every part of the globe. Unproductive granite soils cover nearly 
the whole of Scotland, north of the Grampians, as well as large 
tracts of land in Devon and Cornwall, and on the east and west 
of Ireland. On the other hand, fertile trap soils extend over 
thousands of square miles in the lowlands of Scotland, and in the 
north of Ireland ; and where in Cornwall they occasionally mix 
with the granite soils, they are found to redeem the latter from 
their natural barrenness. 

But while such is the general rule in regard to these two 
classes of soils, it happens on some spots that the presence of 
other minerals in the granites, or of hornblende or mica in 
larger quantity than usual, gives rise to a granitic soil of average " 
fertility, as is the case in the Scilly Isles. In like manner, the 
trap rocks are sometimes, as in parts of the Isle of Skye, so- 
peculiar in their composition as to condemn the land to almost 
hopeless infertility. 

h. Why in some districts the decayed traps, under the local 
names of Rotten rock, Marl, kc, are dug up, and applied with 
advantage, as a top-dressing, to other kinds of land. They 
afford supplies of lime, magnesia, &c., of which the soils they 
are found to benefit may be naturally deficient. And as, by 
admixture with the decayed trap, the granitic soils of Cornwall 
are known to be improved in quality, so an admixture of decayed 



108 LIMING OF TRAP SOILS. 

granite with many trap soils, were it readily accessible, might 
add to the fertility of the latter also. 

c. Why the application of lime in certain trap districts adds 
nothing to the fertility of the land. The late Mr. Oliver of 
Lochend informed me that he had never known a case in which 
the application of lime within five miles of Edinburgh had done 
any good. This he accounted for from the vast number of 
oyster shells which are mixed with the town dung laid on by the 
Edinburgh farmers. Another important reason, however, is the 
abundance of lime contained in the trap rocks from which the 
soils are formed, and of which they contain so many fragments. 
A piece of decaying trap I lately picked up on the north side 
of the Pentland hills, on the farm of Swanstone, was found in 
my laboratory to contain as much as 16 per cent of carbonate 
of lime. 

d. Why, as in many parts of the counties of Ayr and Eife, 
the application of lime is found to be useful when the trap soils 
are first broken up or reclaimed, but to produce little sensible 
benefit for twenty or thirty years afterwards, however frequently 
applied. In these cases the lime has been washed out of .the 
surface soil, and from the thoroughly decayed parts of the trap, 
so that, when first broken up, lime is necessary to supply the 
deficiency. But the constant turning up of the soil by the after- 
cultivation exposes fresh portions of trap to the air, the decay 
of which annually supplies a quantity of lime to the soil from the 
rocky fragments themselves, and renders further artificial appli- 
cations less necessary. I have picked up a piece of decaying 
trap, of which the outer portion contained scarcely any lime, 
while the central kernel contained a large proportion. The 
plough and harrow break up such decaying masses, and expose 
the undecomposed kernels to the weathering action of the atmo- 
sphere, and to the roots of the growing crops. 

3. The Lavas which often cover large tracts of country, where 
active or extinct volcanoes exist, are composed essentially of the 
same mineral substances as the trap rocks. These latter, indeed, 



APPARENT DIFFICULTIES. 109 

are in general only lavas of a more ancient date. Like the 
traps, the lavas not unfrequently abound in hornblende or augite, 
and consequently in lime. They also crumble, with various 
degrees of rapidity, when exposed to the air, and in Italy and 
Sicily often form soils of the most fertile description. Like the 
traps also, when in a decayed state, they may be advantageously 
employed for the improvement of less fruitful soils. In St. 
Michael's, one of the Azores, the natives pound the volcanic 
matter and spread it on the ground, w^here it speedily becomes 
a rich mould, capable of bearing luxuriant crops. 

SECTION II. OF THE SUPERFICIAL ACCUMULATIONS OF TRANSPORTED 

MATERIALS ON DIFFERENT PARTS OF THE EARTH's SURFACE, AND 
THEIR RELATIONS TO THE SOIL. 

It is necessary to guard the reader against disappointment 
when he proceeds to examine the relations which exist between 
the soils and the rocks on which they lie, or to infer the quality 
of the soil from the known nature of the rock on which it rests 
— ^in conforpiity with what has been above laid down — by ex- 
plaining another class of geological appearances, which present 
themselves not only in our own country, but in almost every 
other part of the globe. 

The unlearned reader of the preceding section and chapter 
may say — I know excellent land resting upon the granites, fine 
turnip soils on the Oxford or London clays, tracts of fertile fields 
on the coal measures, and poor gravelly farms on the boasted 
new red sandstone : I have no faith in theory — I can have none 
in theories which are so obviously contradicted by natural ap- 
pearances. Such, it is to be feared, is the hasty mode of rea- 
soning among too many locally* excellent practical men — 

* By locally excellent, I mean those who are the best possible farmers on 
their own districts and after their own way, but who would fail in other 
districts requiring other methods. To the possessor of agricultural princi- 
ples, the modifications required by difference of crop, soil, and cUmate, 



110 ' LOOSE, TRANSPORTED MATERIALS. 

familiar, it may be, with many useful and important facts, but 
untaught to look through and beyond isolated facts to the 
principles on which they depend. 

Every one who has lived long on the more exposed shores of 
our island, has seen that, when the weather is dry, and the sea- 
winds blow strong, the sands of the beach are carried inland and 
spread over the soil, sometimes to a considerable distance from 
the coast. In some countries this sand-drift takes place to a 
very great extent, travels over a great stretch of country, and 
gradually swallows up large tracts of fertile land, and converts 
them into sandy deserts. 

Again, most people are familiar with the fact, that during 
periods of long continued rain, when the rivers are flooded and 
overflow their banks, they not unfrequently bear with them loads 
of sand and gravel, which they carry far and wide, and strew at 
intervals over the surface soil. 

So the annual overflowings of the Nile, the Ganges, the Mis- 
sissippi, and the river of the Amazons, gradually deposit accu- 
mulations of soil over surfaces of great extent ; — and so also the 
bottoms of most lakes are covered with thick beds of sand, gravel 
and clay, which have been conveyed into them from the higher 
grounds by the rivers which flow into them. Over the bottom 
of the sea also, the ruins of the land are spread. Torn by the 
waves from the crumbling shore, or carried down from great 
distances by the rivers which lose themselves in the sea, they 
form beds of mud, or banks of sand and gravel of great extent, 
which cover and conceal the rocks on which they lie. 

To these and similar agencies, a large portion of the existing 
dry land of the globe has been, and is still, exposed. Hence, 
in many places, the rocks and the soils naturally derived from 
them are buried beneath accumulated heaps of layers of sand, 
gravel, and clay, which have been brought from a greater or 
less distance, and which have not unfrequently been derived 

readily suggest themselves, where the mere practical man is bewildered, 
disheartened, and in despair. 



CIRCUMSTANCES TO BE CONSIDERED. Ill 

from rocks of a totally different kind from those of the districts 
in which they are now found. On these accumulations of trans- 
;ported materials, a soil is produced which often has no relation 
in its characters to the rocks v.hich cover the country, and the 
nature of which soils, therefore, a familiar acquaintance with 
the rocks on which they immediately rest would not enable us to 
predict. 

To this cause is due that discordance between the first indi- 
cations of geology, as to the origin of soils from the rocks on 
which they rest, and the actually observed characters of those 
soils in certain districts — of which discordance mention has been 
made as likely to awaken doubt and distrust in the mind of the 
less instructed student, in regard to the predictions of agricul- 
tural geology. There are several circumstances, however, by 
which the careful observer is materially aided in endeavoring to 
understand what the nature of the soils is likely to be in any 
given district, and how they ought to be treated even when the 
subjacent rocks are thus overlaid by masses of drifted materials. 
Thus— 

1. It not unfrequently happens that the materials brought 
from a distance are more or less mixed up with the fragments 
and decayed matter of the rocks which are native to the spot, 
— so that, though modified in quality, the soil nevertheless 
retains the general characters of that which is formed in other 
places from the decay of these rocks alone. 

2. Where the formation is extensive, or covers a large area, 
— as the new red sandstones and coal measures do in this coun- 
try, the mountain limestones in Ireland, and the granites in the 
north of Scotland, — the transported sand, gravel, or clay, 
strewed over one part of the formation, has not unfrequently 
been derived from the rocks of another part of the savie for- 
mation ; so that, after all, the soils may be said to be produced 
from the rocks on which they rest, and may be judged of from 
the known composition of these rocks. 

3. Or if not from the rocks of the same formation, they 



112 SOILS OVERLAP THEIR NATURAL LIMITS. 

have most frequently been derived from those of a neighboring 
formation — from rocks which are to be found at no great distance, 
geologically, and generally on higher ground. Thus the ruins 
of the millstone-grit rocks are in this country often spread over 
the surface of the coal measures — of these, again, over the 
magnesian limestone — of the latter over the new red sand- 
stone, and so on. The effect of this kind of transport of the 
loose materials upon the character of the soils is merely to 
overlap, as it were, the edges of one formation with the proper 
soils of the formations that adjoin it, in the particular direction 
from which the drifted materials are known to have come. 

It appears, therefore, that the occurrence on certain spots, or 
tracts of country, of soils that have no apparent relation to the 
rocks on which they immediately rest, tends in no way to 
throw doubt upon, to discredit or to disprove, the conclusions 
drawn from the more general facts and principles of geology. 
It is still generally true that soils are derived from the rocks on 
which they rest. The exceptions are local, and the difficulties 
which these local exceptions present, require only from agricul- 
tural geologists a more careful study of the structure of eacji 
district — of the direction of the highlands — the nature of the 
slopes — the course and width of the valleys — and the extent of 
the plains, — before they pronounce a decided opinion as to the 
degree of fertility which the soil either naturally possesses, or 
by skilful cultivation may be made to attain. 

^ It is not to be denied, however, that the practical importance 
of these local exceptions is becoming every day more manifest, 
and the necessity more apparent for a careful recording and 
mapping of them in the interests of agriculture. Riding over 
the country, for example, due north from the city of Durham, 
a distance of about three miles, till we are stopped by a bend 
of the river Wear, the superficial covering, so far as it can be 
seen, is represented by the subjoined section. 



DRIFT COVERING NEAR DURHAM. 



113 



No. 7. 



Red Hills 



Bishop's 
Grange. 




1. Yellow unstratiSed hard clay with small stones and 
boulders, forming cold impervious clay soils, 3 to 40 feet. 

2. Yellow sand, loose, with fragments of drifted coal and 
sandstone gravel and boulders, forming potato, barley, and light 
turnip soils, 10 to 100 feet. 

3. Blue unstratified clay, with boulders — often wanting — 10 
to 30 feet. 

4. The coal measures lying beneath. 

All the country being covered, as this section represents, 
with from 30 to 120 feet of superficial sands and clays, it is 
obvious that it can be of comparatively little use to me to know 
that the sandstones and shales of the coal measures lie far 
below ; and though I know that the sands and clays are all 
derived from the crumbled beds of the coal measures, yet they 
give me no information respecting the sandy nature of the soils 
near Kimblesworth, or that they are cold and clayey about 
Bishop's Grange. The nature of the soil in each portion of the 
district — and the same is true of a large portion of the county 
of Durham — depends upon whether the clay or the sand comes 
to the surface. This can only be shown upon special maps, rig- 
orously prepared for the purpose ; and these the progress of 
scientific agriculture will soon render indispensable. 

SECTION III. GENERAL UNIFORMITY IN THE AGRICULTURAL CHAR- 
ACTER OF THE ROCKS AND SOILS ON GEOLOGICAL FORMATIONS OF 
THE SAME AGE. 



And yet there is a wonderful degree of general uniformity in 



114 UNIFORMITY IN THE AGRICULTURAL CHARACTER 

the mineral character and agricultural capabilities of the same 
geological formation in different countries, even when they lie at 
great distances from each other. I have already alluded, for 
example, in a preceding chapter,* to the natural dryness of the 
belt of chalk which runs along the Atlantic border of the 
United States. The scarcity of water experienced by those 
who reside upon it is often great. Every one knows that the 
same is true of our own chalk region in England, and that this 
very materially affects its agricultural capabilities. It is famil- 
iar to every one also, that in very many places wells are sunk 
through it with the view of reaching water, and that in London 
great depths are gone to, and at a vast expense, through the 
London clay and the chalk, before water can be obtained. In 
the Paris basin the chalk is equally dry ; and there are very 
few who have not read of the remarkably deep w^ell at Grenelle 
in the neighborhood of Paris, which, like the less profound 
London wells, has been sunk to the sands below the chalks, and 
with similar success. 

So, in the remote State of Alabama, on this formation, water 
is only to be obtained by sinking through the chalk ; and there 
also this circumstance modifies in a wonderful degree the gene- 
ral dispositions of rural economy. Three years ago there were 
already about 500 wells in that State, sunk to a depth of from 
400 to 600 feet, there being one generally upon each i^lantatiou. 
And thus, while the climate there, as elsewhere, determines the 
general character of the vegetable produce, and what kind of 
plants under the meteorological conditions can arrive at perfec- 
tion, yet the geological structure determines, and enables us to 
judge beforehand, to a certain extent, whether or not any crops 
shall be able to grow at all, and of the kind of plants suitable 
to the climate, which can be profitably cultivated, under the 
circumstances of soil and dryness, which that geological structure 
implies. 

* See the diagram in p. 91. 



OF SOILS OF THE SAME FORMATION. 115 

I may here remark, that, in this case of Alabama, the geo- 
logical structure determines more. In such a climate, and with 
a soil so naturally arid, abundant water is indispensable ; but 
this can only be obtained by deep boring, performed at a great 
expense. The geological conditions, therefore, confine the pos- 
sibility of cultivation to men of large means, and, in present 
circumstances at least, necessarily exclude all petty farming and 
the subdivision of the land into small holdings. They deter- 
mine, in other words, the social condition of the people. This 
single illustration is enough of itself to satisfy any impartial 
person of the close general relation which exists between the 
geological character and the agricultural capability of a coun- 
try, and of the broad general deductions in regard to its possible 
future prosperity — in a rural sense — which may be drawn from 
a knowledge of its geology. I believe it is partly under the 
influence of this conviction that the Senate and Congress of the 
United States have so often and so cordially voted large sums 
of money for the purpose of investigating and mapping the 
main geological features of the new States and territories which 
from time to time have been admitted into the Union. 

Geological majps, such as those now referred to, indicate with 
more or less precision the extent of country over which the 
chalk, the red sandstone, the granites, &c., are found immedi- 
ately beneath the loose materials on the surface. Such maps, 
therefore, are of great value in indicating also the general qual- 
ity of the soils over the same districts. It may be true, as I 
have above explained, that here and there the natural soils are 
masked or buried by transported materials — yet the 'political 
economist may, nevertheless, with safety estimate the general 
agricultural capabilities and resources of a country by the study 
of its geological structure — the capitalist judge in what part of 
it he is likely to meet with an agreeable or profitable investment 
— and the practical farmer in what country he may expect to 
find land that will best reward his labors, that will admit of 
the kind of culture to which he is most accustomed, or, by the 



116 GEOLOGY NOT PERFECT. 

application of better methods, will manifest the greatest agri- 
cultural improvement. 

There are many cases also in which geology, leaving the hum- 
bler task of explaining why certain regions exhibit, or are capa- 
ble of exhibiting, singular natural fertility, or the reverse, 
advances to the higher gift of prediction. United theory and 
observation enable it not only to point out where rich and 
desirable lands are sure to be found — to inform the statesman 
as to the true value of regions still wild and neglected — to 
direct the agricultural emigrant in the choice of new homes — 
but looking far into the future, to specify also the kind of popu- 
lation and the processes of industry which will hereafter prevail 
upon it — the comparative comfort, wealth, numbers, and even 
morality, of its future people. 

That there are certain cases in which geology finds herself at 
fault, or her general deductions unsupported by the reality, is 
only a proof that it is a part of human science, rapidly pro- 
gressive, but still full of imperfections. 



CHAPTER IX. 

Of the physical, chemical, and botanical relations of soils. — Physical proper- 
ties. — Density, absorbent, and evaporative powers, capillary action, 
shrinkage, absorption of moisture from the air, and of heat from the sun. 
— Functions of soils in reference to vegetation. — Chemical composition and 
analysis of soils. — Comparative composition of certain fertile and barren 
soUs. — Importance of certain forms of organic matter to the fertility of a 
soil. — The black earth of central Russia. — Direct relation between the 
character of the soil and the kind of plants that naturally grow upon it. 

Soils formed, as we have described, from the ruins of crumb- 
led rocks, more or less sorted and drifted by water, possess 
three classes of properties, intimately related to each other, 
and to their special agricultural value. These are their phy- 
sical, chemical, and botanical properties. A brief consideration 
of these will form the subject of the present chapter. 

SECTION I. OF THE PHYSICAL PROPERTIES OF SOILS. 

1°. Density. — Some soils are heavier and denser than others, 
sands and marls weighing most and dry peaty soils the least. 
This density is of so much practical importance, that treading 
with sheep and other stock is resorted to in many districts, 
with the view of rendering the land more solid ; or heavy 
rollers are passed over it, to prepare a firm seed-bed for the 
corn. Also, in reclaiming peaty soils, it is found highly bene- 
ficial to increase their density by a covering of clay or sand, or, 
'as in Ireland, of limestone gravel. 

2°. Absorption of water. — Again, some soils absorb the 
rains that fall, and retain them in larger quantity and for a 
longer period than others. Strong clays absorb and retain 
nearly three times as much water as sandy soils do, while peaty 



118 PHYSICAL PROPERTIES OF SOILS. 

soils absorb a still larger proportion. Hence the more fre- 
quent necessity for draining clayey than sandy soils ; and hence 
also the reason why, in peaty land, the drains must be kept 
carefully open, in order that the access of springs and of other 
water from beneath may be as much as possible prevented. 

3°. The ca/pillary action of soils also differs. Some, when 
immersed in water, will become moist, or attract the water 
upwards for 10 or 12 inches, some as many as 16 or 18 inches, 
above the surface of the water. This property is of great 
importance in reference to the growth of plants — to the rising 
of water to the surface of land which rests upon a wet subsoil 
— to the necessity for thorough drainage — to the general 
warmth of the soil, and so on. 

4°. Evaporative jtoioer. — When dry weather comes, soils lose 
water by evaporation with different degrees of rapidity. In 
this way a silicious sand will give off the same weight of water, 
in the form of vapor, in one-third of the time necessary to 
evaporate it from a stiff clay, a peat, or a rich garden mould, 
when all are equally exposed to the air. Hence the reason 
why plants are so soon burned up in a sandy soil. Not only 
do such soils retain less of the rain that falls, but that which is 
retained is also more speedily dissipated by evaporation. 
When rains abound, however, or in very moist seasons, these 
same properties of sandy soils enable them to dry quickly, and 
thus to sustain a luxuriant vegetation at a time when plants 
will perish on clay lands from excess of moisture. 

5°. Shrinkage. — In drying under the influence of the sun, 
soils shrink in, and thus diminish in bulk, in proportion to the 
quantity of .clay or of peaty matter they contain. Sand 
scarcely diminishes at all in bulk by drying, but peat shrinks 
one-fifth in bulk, and strong agricultural clay nearly as much. 
The roots are thus compressed and the air excluded from them, 
especially in the hardened clays, in very dry weather, and thus 
the plant is placed in a condition unfavorable to its growth. 
Hence the value of proper admixtures of sand and clay. By 



TEMPERATURE OF A SOIL. 119 

the latter (the clay) a sufficient quantity of moisture is re- 
tained, and for a sufficient length of time ; while by the former 
the roots are preserved from compression, and a free access of 
the air is permitted. 

6°. Ahsorjption of moisture from the air, — In the hottest and- 
most drying weather, the soil has seasons of respite from the 
scorching influence of the sun. During the cooler season of 
the night, even when no perceptible dew falls, it has the power 
of again extracting from the air a portion of the moisture it 
had lost during the day. Perfectly pure sand possesses this 
power in the least degree ; it absorbs little or no moisture 
from the air. A stiff day, on the other hand, ivill, in a single 
night, absorb sometimes a ZOth part of its own weight, and a dry 
peat as much as a 12th of its weight ; and, generally, the quan- 
tity thus drunk in, by soils of various qualities, is dependent 
upon the proportions of clay and vegetable m.atter they seve- 
rally contain. We cannot fail to perceive from these facts, 
how much the productive capabilities of a soil are dependent 
upon the proportions in which its different earthy and vegetable 
constituents are mixed together. 

^^. The temperature of a soil, or tlie degree of warmth it 
is capable of attaining under the influence of the sun's rays, 
materially afi*ects the progress of vegetation. Every gardener 
knows how much bottom heat forces the growth, especially of 
young plants ; and wherever a natural warmth exists in the 
soil, independent of the sun, as in the neighborhood of vol- 
canoes, there it exhibits the most exuberant fertility. One 
main influence of the sun in spring and summer is dependent 
upon its power of thus warming the soil around the young 
roots, and rendering it propitious to their rapid growth. But 
the sun does not warm all soils alike — some become much 
hotter than others, though exposed to the same sunshine. 
When the temperature of the air in the shade is no higher 
than 60°, or 70°, a dry soil may become so warm as to raise the 
thermometer to 90° or 100°. Mrs. Ellis states, that among 



120 INFLUENCE OF THE SUN. 

the Pyrenees the rocks actnally smoke after rain, under the 
influence of the summer sun, and become so hot that you can- 
not sit down upon them. In Central Australia, where the 
thermometer is sometimes as high as 132° F. in the shade, and 
15*1° in the sunshine, the ground becomes so hot that it kindles 
matches that fall on it, and burns the skin off the dogs' feet. 
In wet soils the temperature rises more slowly, and rarely 
attains the same height as in a dry soil by 10° or 15°. Hence 
it is strictly correct to say, that wet soils are cold ; and it is 
easy to understand how this coldness is removed by perfect 
drainage.* Dry sands and clays, and blackish garden mould, 
become warmed to nearly an equal degree under the same sun ; 
brownish-red soils are heated somewhat more, and dark-colored 
peaty soils the most of all. It is probable, therefore, that the 
presence of dark-colored vegetable matter renders the soil 
more absorbent of heat from the sun, and that the color of the 
dark-red marls of the new and old red sandstones may, in 
some degree, aid the other causes of fertility in the soils which 
they produce. * 

In reading the above observations, the practical reader can 
hardly fail to have been struck with the remarkable similarity 
in physical properties between stiff clay and peaty ^oils. 
Both retain inuch of the water that falls in rain, and both 
part with it slowly by evaporation. Both contract much in 
drying, and both absorb moisture readily from the air, in the 
absence of the sun. In this similarity of properties we see 
not only why the first steps in improving both kinds of soil 
must be very nearly the same, but why, also, a mixture either 
of clay or of vegetable matter will equally impart to a sandy 
soil many of those elements of fertility — of which they are 
alike possessed. 

* See the succeeding Chapter. 



CHEMICAL COMPOSITION AND ANALYSIS OF SOILS. 121 



SECTION II. OF THE CHEMICAL COMPOSITION AND ANALYSIS OF 

SOILS. 

Soils perform at least three functions in reference to vege- 
tation. They serve as a basis in which plants may fix their 
roots and sustain themselves in their erect position — they supply 
food to vegetables at every period of their growth — and they 
are the medium in which many chemical changes take place, 
that are essential to a right preparation of the various kinds 
of food which the soil is destined to yield to the growing 
plant. 

We have spoken of soils as consisting chiefly of sand, lime, 
and clay, with certain saline and organic substances in smaller 
and variable proportions. But the study of the ash of plants 
(see chap, iv.) shows us that a fertile soil, besides its organic 
matter, must of necessity contain an appreciable quantity of 
twelve or fourteen different mineral substances, which, in most 
cases, exist in greater or less relative abundance in the ash both 
of wild and of cultivated plants. 

Two well-known geological facts lead to precisely the same 
conclusion. We have seen that the soils formed from the un- 
stratified rocks — the granites and the- traps — while they each 
contain certain earthy substances in proportions peculiar to 
themselves, yet contain also in general, especially the trap 
soils, a trace, of most of the other kinds of matter which are 
found in the ash of plants. Again, it is equally certain that 
the stratified rocks are only the more or less slowly accumu- 
lated fragments and ruins of more ancient stratified or unstra- 
tified masses, which, under various agencies, have gradually 
crumbled to dust, been strewed over the surface in alternate 
layers, and have afterwards again consolidated. The reader 
will readily grant, therefore, that in all rocks, and consequently 
in all soils, traas of every one of these substances may gene-* 
rally be presumed to exist. 
6 



122 GENERAL COMPOSITION OF SOILS. 

Actual cJmnical analysis confirms these deductions in regard 
to the composition of soils. It shows that, in most soils, the 
presence of all the constituents of the ash of plants may be de- 
tected, though in very variable and sometimes in very minute 
proportions ; and, following up its investigations in regard to 
the effect of this difference in their proportions, it establishes 
certain other points of the greatest possible importance to agri- 
cultural practice. Tims, it has found, for example — 

1. That as a proper adjustment of the proportions of clay, 
sand, and vegetable matter, is necessary in order that a soil 
may possess the most favorable ^physical properties, so the 
mere presence of the various kinds of food, organic and inor- 
ganic, in a soil, is not sufficient to make it productive of a given 
crop, but that they must be present in such quantity that the 
plant shall be able readily — at the proper season, and within 
tlie time usually allotted to its growth — to obtain an adequate 
supply of each. 

Thus a soil may contain, on the whole, far more of a given 
ingredient, such as potash, soda, and lime, than the crop we 
have sown may require, and yet, being diffused through a large 
quantity of earth, the roots may be unable to collect this sub- 
stance fast enough to supply the wants of a rapidly growing 
plant. To such a soil it will be necessary tc add a further por- 
tion of what the crop requires. 

Again, a crop of winter wheat, which remains nine or ten 
months in the field, has much more leisure to collect from the 
soils those substances which are necessary to its growth than a 
crop of barley, which in cold climates like that of Sweden is 
only from 6 to 7| weeks in the soil, and which in warm 
countries like Sicily may be reaped twice in the year. Thus a 
soil which refuses to yield a good crop of the quick-growing 
barley may readily nourish a crop of slow-growing wheat. 

2. That when a soil is particularly poor in certain of these 
substances, the valuable cultivated corn crops, grasses, and 



USE OF CHEMICAL ANALYSIS TO AGRICULTURE. 123 

trees, refuse to grow upon them in a healthy manner, and to 
yield remunerating returns. And, 

3. That when certain other substances are present in too 
great abundance, the soil is rendered equally unpropitious to 
the most important crops. 

In these facts the intelligent reader will perceive the founda- 
tion of the varied applications to the soil which are everywhere 
made under the direction of a skilful practice — and of the diffi- 
culties which, in many localities, lie in the way of bringing the 
land into such a state as shall fit it readily to supply all the 
wants of those kinds of vegetables which it is the special ob- 
ject of artificial culture easily and abundantly to raise. 

Chemical analysis is a difficult art — one which demands much 
chemical knowledge, as well as skill in chemical practice; 
(manipulation, as it is called,) and calls for both time and per- 
severance — if valuable, trustworthy, and minutely correct results 
are to be obtained. I believe it is only by aiming after such 
minutely correct results that chemical analysis is likely to throw 
light on the peculiar properties of those soils which, while they 
possess much general similarity in composition and physical pro- 
perties, are yet found in practice to possess very difierent agri- 
cultural capabilities. Many such cases occur in every country, 
and they present the kind of difficulties in regard to which 
agriculture has a right to say to chemistry — "These are mat- 
ters which I hope and expect you will satisfactorily clear up." 
But while agriculture has a right to use such language, she has 
herself preliminary duties to perform. She has no right in one 
breath to deny the value of chemical theory to agricultural 
practice, and in another to ask the sacrifice of time and labor 
in doing "her chemical work. Chemistry is a wide field, and 
many zealous lives are now being spent in the prosecution of it, 
without at all entering upon the domain of practical agriculture. 
It may be that here and there it may fall in with the humor or 
natural bias of some one chemist to apply his knowledge to this 
most important art; but hitherto the appreciation of such efforts 



124: CLAY AND SAND IN SOILS. 

has, except by a limited few, been so small — the reception of 
scientific results and suggestions by the agricultural body gene- 
rally so ungracious — that little wonder can exist that so many 
chemists have quitted the field in disgust — that the majority of 
capable men should studiously avoid it. 

SECTION III. COMPARATIVE COMPOSITION OF FERTILE AND 

BARREN SOILS. 

With the view of illustrating the deductions which, as above 
stated, may be drawn from an accurate chemical analysis, I 
shall exhibit the composition of three different soils, as deter- 
mined by Sprengel, a German agricultural chemist. 
, No. 1 is a very fertile alluvial soil from East Friesland, for- 
merly overflowed by the sea, but for sixty years cultivated with 
corn and pulse crops, without manure. 

No. 2 is a fertile soil near Gottingen, which produces excel- 
lent crops of clover, pulse, rape, potatoes, and turnips, the two 
last more especially when manured with gypsum. 

No. 3 is a very barren soil from Luneberg. 

When washed with water in the manner described in page 
Y6, they give respectively, from 1000 parts of soil — 





No. 1. 


No. 2. 


No. 3. 


Soluble saline matter, 

Fine clay and organic matter, 

Silicious sand, 


18 

. 937 

45 


1 

839 
IGO 


1 
599 
400 



1000 1000 1000 

The most striking distinction presented by these numbers is 
the large quantity of saline matter in No. 1. This soluble mat- 
ter consisted of common salt, chloride of potassium, sulphate of 
potash, and- sulphate of lime, (gypsum,) with traces of sulphate 
of magnesia, sulphate of iron, and phosphate of soda. The 
presence of this comparatively large quantity of these different 
saline substances — originally derived, no doubt, in great part 



COMPOSITION OF CERTAIN SOILS BY ANALYSIS. 



125 



from the sea — was prol3ably oiie reason why it could be so long 
cropped Avithout manure. 

The unfruitful soil is much the lightest (in the agricultural 
sense) of the three, containing 40 per cent of sand; but this is 
not enough to account for its barrenness, many light soils con- 
taining a larger proportion of sand, and yet being sufficiently 
fertile. 

The finer portions, separated from the sand and soluble mat- 
ter, consisted, in 1000 parts, of — 



Organic matter, 
Silica, 

Alumina, . 
Lime, 

Magnesia, . 
Oxide of iron, . 
Oxide of manganese. 
Potash, 
Soda, 
Ammonia, 
Chlorine, . 
Sulphuric acid, . 
Phosphoric acid, 
Carbonic acid, . 
Loss, . 



No. 1. 


No. 2. 


No. 3, 


97 


50 


40 


648 


833 


778 


57 


51 


91 


59 


18 


4 


8i 


8 


1 


61 


30 


81 


1 


3 


i 


2 


trace. 


trace. 


4 


do. 


do. 


trace. 


do. 


do. 


2 


do. 


do. 


2 


4 


do. 


H 


11 


do. 


40 


U 


do. 


14 




U 



1000 



1000 



1000 



1 . The composition of 'No. 1 illustrates the first of the general 
deductions stated in the preceding section — that a considerable 
supply, namely, of all the species of inorganic food is necessary 
to render a soil eminently fertile. Kot only does this soil contain 
a comparatively large quantity of soluble saline matter, but it 
contains also nearly 10 per cent of organic matter, and what, 
in connection with this, is of great importance, nearly 6 per 
cent of lime. The potash and soda, and the several acids, are 
also present in sufficient abundance. 

2. In the second — a fertile soil, but one which cannot disjpense 
with manure — there is little soluble saline matter, and in the 
insoluble portion we see that there are mere traas only of 



126 PRACTICAL DEDUCTIONS. 

potash, soda, and the important acids. It contains also only 5 
per cent of organic matter, and less than 2 per cent of lime; 
which smaller proportions, together with the deficiencies above 
stated, remove this soil from the most naturally fertile class to 
that class which is susceptible, in hands of ordinary skill, of 
being hrought to^ and kejpt in, a very productive condition. 

3. In the fine part of the third soil, we observe that there 
are many more substances deficient than in No. 2. The organic 
matter amounts apparently to 4 per cent, and there seems to be 
nearly half a per cent of lime. But it will be recollected that 
this soil contains 40 per cent of sand, (p. 125;) or that in every 
hundred of soil there are only 60 of the fine matter, of which 
the composition is presented in the table; — or 100 lb. of the 
native soil contain only 2| lb. of organic matter and \ lb. of 
lime. 

But all these wants would not alone condemn the soil to 
hopeless barrenness, because, in favorable circumstances, they 
might all be supplied by art. But the oxide of iron amounts to 
8 per cent of this fine part of the soil ; a proportion of this sub- 
stance which, in a soil containing so little lime and organic mat- 
ter, appears, from practical experience, to be incompatible with 
the healthy growth of cultivated crops. This soil, therefore, 
requires, not only those substances of which it is destitute, but 
such other substances also, or such a form of treatment, as shall 
prevent the injurious effects of the large portion of oxide of iron 
it contains. 

In these three soils, therefore, we have examples, fitst, of one 
which contains within itself all the elements of fertility ; second, 
of a soil which is destitute, or nearly so, of certain substances 
required by plants, which, however, can be readily added by the 
ordinary manures in general use, and to which the elements of 
gypsum are especially useful, in aiding it to feed the potato and 
the turnip; and third, of a soil not only poor in many of the 
necessary species of the inorganic food of plants, but too rich 



THE BLACK EARTH OF RUSSIA. 12t 

in one (oxide of iron) which, when present in excess, is usually 
prejudicial to vegetable life. 

This illustration, therefore, will aid the general reader in 
comprehending how far rigid chemical analysis is fitted to 
throw light upon the capabilities of soils, and to direct agricul- 
tural practice. 

SECTIOX IV. IMPORTANCE OF CERTAIN FORMS AND QUANTITIES OF 

ORGANIC MATTER TO THE FERTILITY OF A SOIL. 

The hlack earth of Russia. — The Tchornoi Zem, or black earth 
of Central Russia, illustrates, in a very striking manner, the 
fact, that the kind and quantity of the organic matter which a 
soil contains are scarcely less influential upon its fertihty than 
the mineral constituents to which, in the last section, I prin- 
cipally adverted. This remarkable black soil, ''the finest in 
Russia, whether for the production of wheat or grass," covers 
an area of upwards of 60,000 square geographical miles, and is 
said to be everywhere of extreme and of nearly uniform fer- 
tility. It nourishes a population of more than twenty millions 
of souls, and yet annually exports upwards of fifty millions of 
bushels of corn. This black earth stretches into Hungary, and 
forms the largest extent of fertile soil possessing common and 
uniform qualities which is anywhere known to exist. Its origin 
and chemical composition, therefore, have naturally engaged 
the attention both of scientific and of practical observers. 

Its depth varies from 1 or 2 to 20 feet ; when moist, it is 
jet black, and when dry, of a dark brown. This dark color, 
from which it derives its name, is due to the presence of or- 
ganic, chiefly vegetable matter, in a peculiar decomposed state, 
minutely divided and intimately mixed with mineral matter. 
Of the weight of the dry soil, it forms, in different samples, 
from 6 to 18 per cent. This vegetable matter is distinguished 
by two circumstances. 

1. That it is in an exceedingly minute state of division, and 



128 ANALYSIS OF THE BLACK EARTH, 

is intimately mixed with finely-divided mineral matter. The 
black earth, therefore, forms a comparatively free and open 
soil, into which the air penetrates and the roots of plants 
descend freely. 

2. It contains in a state of combination a considerable pro- 
portion of nitrogen. In different samples this constituent has 
been found to vary from 21 (Payen) to eight per cent (Schmidt) 
of the weight of the organic matter. Through the action of 
the air, this nitrogen will favor the production in the soil of 
nitric acid, ammonia, and other soluble compounds containing 
nitrogen, which I have already described as propitious to the 
growth of plants. 

But in this black earth the composition of the mineral or 
inorganic part is also such as to promote fertility. In one 
of the richest varieties, in which the organic matter amounted 
to 18 per cent, the mineral matter was found to consist of — 

Per cent. 

Potash, 5.81 

Soda, • 2.31 

Lime, 2.60 

Magnesia., 0.95 

Alumina and oxide of iron, with traces of 

phosphoric acid, .... . 17.32 

Silica, of which 1 or 8 per cent were soluble, T 0.94 



99.93 

We see in this analysis an abundant supply of those mineral 
substances which appear to be so necessary to the healthy 
growth of plants. 

The general results of our analytical examination of soils, 
therefore, are chiefly these — 

a. That a due admixture of organic matter is favorable to 
the fertility of a soil. 

h. That this organic matter will prove the more valuable in 
proportion to the quantity of nitrogen it holds in combination. 

c. That the mineral part of the soil must contain all those 
substances which are met with in the ash of the plant, and in 



AND CAUSES OF ITS FERTILITY. 120 

such a state of chemical combination that the roots of plants 
can readily take them up in the requisite proportion. 

It is to the long accumulation of the remains of forests, or 
other abundant aucient vegetation, that the color of the Black 
earth, and its richness in organic matter, is, with the greatest 
probability, ascribed. 

SECTION V. — OF THE DIRECT RELATION THAT EXISTS BETWEEN THE 
CHARACTER OF THE SOIL AND THE KIND OF PLANTS THAT NATU- 
RALLY GROW UPON IT. 

The importance of a minute study of the chemical composi- 
tion of soils will, perhaps, be most readily appreciated by a 
glance at the very different kinds of vegetables which, under 
the same circumstances, different soils naturally produce ; in 
other words, by a glance at their botanical relations. 

There are none so little skilled in regard to the capabilities of 
the soil, as not to be aware that some lands naturally produce 
abundant herbage or rich crops, while others refuse to yield a 
nourishing pasture, and are deaf to the often-repeated solicita- 
tions of the diligent husbandman. There exists, therefore, a 
universally understood connection between the kind of soil and 
the kind of plants that naturally grow upon it. It is interest- 
ing to observe how close this relation in many cases is. 

1. The sands of the sea-shore, the margins of salt lakes and 
the surfaces of salt plains, like the Russian steppes, are distin- 
guished by their peculiar tribes of salt-loving plants — by varie- 
ties of salsola, salicornia, &c. The Triticum junceum (sea 
wheat) grows on the seaward slopes of the downs at no great 
distance from the sea. The drifted sands more removed from 
the beach produce their own long, waving, coarser grass, — the 
Arundo arenaria, (sea bent,) the Elymus arenarius, (sea lime 
grass,) and the Carex arenarius, (sand sedge,) the roots of 
which plants bind the shifting sands together The beautiful 
6* 



130 PLANTS SELECT THE SOILS 

sea pmk spreads itself over the loose downs — while further 
inland, and as the soil changes, new vegetable races appear. 

2. The peaty hills and flats of our island naturally clothe 
themselves with the common ling, ( Calluna vulgaris^ ) the fine- 
leaved heath, {Erica cinerea,) and with the cross-leaved heath, 
{Erica tetralix.) When drained and laid down to grass, or 
when they exist as natural meadows, they produce one soft 
woolly grass almost exclusively — the Holms lanatus. After 
they are limed, these same soils become propitious to greeu 
crops and produce much straw, but refuse to fill the ear. The 
grain is thick-skinned, and therefore light in flour. There is a 
greater tendency to produce cellular fibre, and the insoluble 
matter associated with it, than the more useful substances starch 
and gluten. 

3. On the margins of water-courses in which silica abounds, 
the mare's tail {Equisetum) springs up in abundance : while, if 
the stream contain much carbonate of lime, the water-cress 
appears and Hues the sides and bottom of its shallow bed, some- 
times for many miles from its source. 

4. The Cornish heath (Erica vagans) shows itself rarely 
above any other than the serpentine rocks ; the red broom- 
rape, (Orohanche rubra,) only on trap or basaltic rocks ; the 
Anemone pulsatilla on the dry banks of chalky mounds, as in 
the neighborhood of Newmarket ; the lady's slipper on calca- 
reous formations only ; the Medicago lupulina on soils which 
abound in marl ; while the red clover and the vetch delight in 
the presence of gypsum, and the white clover in that of alka- 
line matter in the soil. 

So the red and white fire-weeds, Epilobium coloratum, and 
Erichtites hierecif alius, cover with their bright blossoms every 
open space in the jN'orth American woods, over which the fires, 
so frequent there, have run during the previous year. The 
ashes of the burned trees and underwood are specially grateful 
to the seeds of these plants, which in vast quantities lie dor- 
mant in the soils. 



ON WHICH THEY TREFER TO GROAV. 131 

5. The clays, too, have their likings. The Rest harrow, 
(Ononis arvensis,) delights in the weald, the gault, and the 
plastic clays, but passes by the green-sand and chalk soils, by 
which these chxys are separated from each other. The oak, in 
like manner, characterises the clays of the weald ; while the 
elm flomnshes, in preference, on the neighboring soils of the 
green-sand formation. 

6. Then, again, plants seem to alternate with each other on 
the same soil. Burn down a forest of pines in Sweden, and 
one of birch takes its place for a while. The pines after a 
time again spring up, and ultimately supersede the birch. The 
same takes place naturally. On the shores of the Rhine are 
seen ancient forests of oak from two to four centuries old, gra- 
dually giving place at present to a natural growth of beech, 
and others where the pine is succeeding to both. In the Pala- 
tinate, the ancient oak-woods are followed by natural pines; 
and in the Jura, the Tyrol, and Bohemia, the pine alternates 
with the beech. 

These and other similar difterences are believed to depend in 
great part upon the chemical composition of the soil. The slug 
may live well upon, and therefore infest, a field almost deficient 
in lime ; the common land snail will abound at the roots of the 
hedges only v/here lime is plentiful, and can easily be obtained 
for the construction of its shell. So it is with plants. Each 
grows spontaneously where its wants can be most fully and 
most easily supplied. If they cannot move from place to place 
like the living animal, yet their seeds can lie dormant, until 
either the hand of man or the operation of natural causes pro- 
duces such a change in their position, in reference to light, 
heat, &c., as to give them an opportunity of growing — or in 
the composition and physical qualities of the soil itself, as to fit 
it for ministering to their most important wants. 

And such changes do naturally come over the soil. The oak, 
after thriving for long generations on a particular spot, gradu- 
ally sickens ; its entire race dies out, and other races succeed it. 



132 PLANTS SICKEN ON SOME SOILS. 

Has the operation of natural causes gradually removed from 
the soil that which favored the oak, and introduced or given 
the predominance to those substances which favor the beech or 
the pine ? On the light soils of the state of New Jersey tlie 
peach tree used to thrive better than anything else, and large 
sums of money were made from the peach grounds in that 
state. But of late years they have almost entirely failed. In 
Scotland, the Scotch fir has been known at once to die out over 
an area of 500 or GOO acres — and the forests of larch are now 
in many localities exhibiting a similar decay. This decay is 
often, I believe, owing to the presence of noxious matters in 
the subsoil, but it is due in some cases also to a natural change 
in the composition and character of the several soils, which has 
taken place since the peach, the fir, and the larch trees were 
first planted upon them. 

In the hands of the farmer, the land grows sick of this crop 
— it becomes tired of that. These facts may be regarded as 
indications of a change in the chemical composition of the soil. 
This alteration may proceed slowly and for many years; and 
the same crops may still grow upon it for a succession of rota- 
tions. But at length the change is too great for the plant to 
bear ; it sickens, yields an unhealthy crop, and ultimately refuses 
altogether to grow. 

The plants we raise for food have similar likes and dislikes 
with those that are naturally produced. On some kinds of food 
they thrive: fed with others, they sicken or die. The soil must 
therefore be prepared for their special growth. 

In an artificial rotation of crops we only follov/ nature. One 
kind of crop extracts from the soil a certain quantity of all the 
inorganic constituents of plants, but some of these in much 
larger proportions than others. A second kind of crop carries 
oif, in preference, a large quantity of those substances of which 
the former had taken little; and thus it is clearly seen, both 
why an abundant manuring may so alter the composition of the 
soil as to enable it to grow almost any crop; and why, at the 



AGRICULTURE A CHEMICAL ART. 133 

same time, this soil may, in succession, yield more abundant 
crops, and in greater number, if the kind of plants sown and 
reaped be so varied as to extract from the soil, one after the 
other, the several different substances which the manure we 
have originally added is known to contain. 

So with regard to the organic matter which soils contain. 
That form of organic food which suits one, may not equally favor 
another species of plant, and thus, at different times, different 
species may be most suited to the chemical condition of the 
same field. 

The management and tilUng of the soil, in fact, is a branch 
of practical chemistry which, like the art of dyeing, of lead- 
smelting, or of glass-making, may advance to a certain degree 
of perfection without the aid of pure science,- but which can 
only have its processes explained, and be led on to shorter, more 
simple, more economical, and more perfect processes, by the 
aid of scientific principles. 



CHAPTER X. 

Of the general iraprovement of the soil, and how the prudent man will 
commence such improvement. — Mechanical methods of improving the 
soil. — Draining, cause of the benefits produced by it. — Draining of appa- 
rently dry land. — Summary of the economical advantages of draining. — 
Depth to which drains ought to be dug. — Effects produced by the rains 
as they descend through the soil. 

The soil, in its natural condition, is possessed of certain ex- 
isting and obvious qualities, and of certain other dormant capa- 
bilities. How are the existing qualities to be improved, — the 
dormant capabilities to be awakened ? 

SECTION I. OF THE GENERAL IMPROVEMENT OF THE SOIL, AND HOW 

THE PRUDENT MAN WILL COMMENCE SUCH IMPROVEMENT. 

There are few soils to which something may not still be done 
in the way of improvement, while by far the greatest breadth 
of the land, in almost every country, is still susceptible of ex- 
tensive amelioration. In its present condition, the art of culti- 
vating the land in England generally, differs from nearly all 
other arts practised among us in this — that he who undertakes 
it later in life, who brings to it a mind already matured, a good 
ordinary education, a sound judgment, and a fair share of pru- 
dence, who turns to it as a new pursuit, is often seen to take 
the lead among the agriculturists of the district in which he 
settles. He comes to the occupation free from the trammels of 
old customs, old methods, and old prejudices, and hence, is free 
to adopt a sounder practice and more rational methods of cul- 
tivation. Such men, from lack of prudence or other causes, 
have not always prospered in their worldly affairs, but they 



GENERAL IMPROVEMENT OF SOILS. 135 

have in very many districts been the beginners of agricultural 
improvements, the introducers of better systems of culture, and 
consequently public benefactors to the country. 

What ought to be the course of such a man in embarking 
any serious amount of capital in this new pursuit ? What that 
of an intelligent practical farmer on establishing himself in a 
new district ? 

Suppose them to be equally well read in the theory and in 
the general practice of agriculture, they will — 

1. Examine the quality of the land, its soil and its subsoil, 
the exposure and the climate, the access to markets and to ma- 
nures ; and generally, they will inquire what, in that district, 
are the more common sources of disappointment to the indus- 
trious farmer. 

2. Consider what, in the abstract, theory would indicate as 
the most proper treatment for such land so situated, and the 
amount of produce it ought to yield. 

3. Inquire what is the actual produce of the land, what the 
actual practice in the district, and especially the cause or rea- 
son of any local peculiarities in the practice which may be 
found to prevail. There are often good reasons for local pecu- 
harities which new settlers injure themselves by overlooking, 
and find out too late for their own interest. The prudent man 
may look with suspicion upon such local customs, but he will 
be satisfied that there is no sufiicieut reason for their adoption, 
before he finally reject them to follow the indications of theory 
alone. 

In illustration of this I may mention, that a friend of mine 
in Ayrshire, in agreeing to become the tenant'of a farm which 
appeared to have been exhausted by the previous occupant, 
founded his hopes of success on ploughing deeper, and thus 
bringing a new soil to the surface, and his anticipations have 
not been disappointed by the result. On the other hand, I 
know of an instance in Berkshire, where, under the direction of 
a new agent, deeper ploughing was introduced, and the crops 



136 IMPROYEMEXT BY DRAINING. 

proved in consequence almost an entire failure. In this case 
sound theory indicated a deeper ploughing, but local experience 
had proved that shallow ploughing alone could preserve the 
crops from the fatal ravages of insect tribes. The local custom 
here, therefore, was founded upon a good reason, one sufficient 
to deter the prudent man from hasty or extensive experiments, 
though not enough to prevent him from seeking out some method 
of so extirpating the insect destroyers from his land, as to enable 
him afterwards to avail himself of its greater depth of soil. 

Suppose it now to be determined that the land is capable of 
being made to yield a larger produce, the questions recur — what 
is the kind of improvement for which this land will give the 
best return ? how is this improvement to be best, most fully, 
and at the same time most economically brought about ? 

All soils may be arranged into one or other of two classes. 

1. Those which, hke No. 1, (p. 125) contain in themselves 
an abundant supply of all those things which plants require, 
and are therefore fitted chemically to grow any crop. 

2. Those which, like Nos. 2 and 3, (p. 126) are deficient in 
some of those substances on which plants live, and are there- 
fore not fitted to grow, perhaps, any one crop with luxuriance. 

Both of these classes of soils, as they are naturally met with, 
are susceptible of improvement, the former by mechanical 
methods chiefly, the latter by mechanical partly, but chiefly by 
chemical methods. In the present chapter we shall consider the 
mechanical methods of improving the soil. 

SECTION II. OF IMPROVING THE SOIL BY DRAINING, AND THE CAUSES 

OF THE BENEFITS PRODUCED BY IT. 

The first step to be taken in order to increase the fertility of 
nearly all the improvable lands of Great Britain, is to drain 
them. The advantages that result from draining are manifold. 

1°. The presence of too much water in the soil keeps it con- 
stantly cold. The heat of the sun's rays, which is intended by 



EFFECTS OF DRAINING. 13*1 

nature to warm the land, is expended in evaporating the water 
from its surface ; and thus the plants never experience that 
genial warmth about their roots which so much favors their 
rapid growth. 

The temperature which a dry soil will attain in the summer 
time is often very great. Sir John Herschel observed, that at 
the Cape of Good Hope the soil attained a temperature of 150° 
Fahrenheit, when that of the air was only 120^ ; and Hum- 
boldt says, that the warmth of the soil between the tropics 
often rises to from 124° to 136°, (see p. 119.) 

When the land is full of water, it is only after long droughts, 
and when it has been thoroughly baked by the sun, that it be- 
gins to attain the temperature which dry land under the same 
sun may have reached, day after day, probably for weeks before. 

2°. Where too much water is present in the soil, also, that 
portion of the food of the plant which the soil supplies is so 
much diluted, that either a much greater quantity of fluid 
must be taken in by the roots — much more work done by them, 
that is — or the plant will be scantily nourished. The presence 
of so much water in the stem and leaves keeps down their tem- 
perature also, when the sunshine appears — an increased evapo- 
ration takes place from their surfaces — a lov/er natural heat, in 
consequence, prevails in the interior of the plant, and the 
chemical changes, on which its growth depends, proceed with 
less rapidity. 

3°. By the removal of the water, the physical properties of 
the soil, also, are in a remarkable degree improved. Dry pipe- 
clay can be easily reduced to a fine powder, but it naturally, 
and of its own accord, runs together when water is poured 
upon it. So it is with clays in the field. When wet, they are 
close, compact, and adhesive, and exclude the air from the 
roots of the growing plant. But remove the water and they 
gradually contract, crack in every direction, become thus open, 
friable, and mellow, more easily and cheaply worked, and per- 
vious to the air in every direction. 



138 DRAINING OF LIGHT SOILS. 

4^. The access of this air is essential to the fertility of the 
soil, and to the healthy growth of most of our cultivated 
crops. The insertion of drains not only makes room for the 
air to enter by removing the water, but actually compels the 
air to penetrate into the under parts of the soil, and renews it 
at every successive fall of rain. Open such outlets for the 
water below, and as this water sinks and trickles away, it will 
suck the air after it, and draw it into the pores of the soil 
wherever itself has been. 

Vegetable matter becomes of double value in a soil thus 
dried and filled with atmospheric air. When drenched with 
water, this vegetable matter either decomposes very slowly, or 
produces acid compounds more or less unwholesome to the 
plant, and even exerts injurious chemical reactions upon the 
earthy and saline constituents of the soil. In the presence of 
air, on the contrary, this vegetable matter decomposes rapidly, 
produces carbonic acid in large quantity, as well as other com- 
pounds on which the plant can live, and even renders the inor- 
ganic constituents of the soil more fitted to enter the roots, 
and thus to supply more rapidly what the several parts of the 
plant require. Hence, on dry land, manures containing organic 
matter, (farmyard manure, &c.,) go farther or are more profit- 
able to the farmer. 

5°. Nor is it only stiff and clayey soils to which draining 
can with advantage be applied. It will be obvious to every 
one, that when springs rise to the surface in sandy soils, a 
drain must be made to carry off the water ; it will also readily 
occur, that where a sandy soil rests upon a hard or clayey 
bottom, drains may likewise be necessary ; but it is not un- 
frequently supposed, that where the subsoil is sand or gravel, 
thorough draining can seldom be required. 

Every one, however, is familiar with the fact, that when 
water is applied to the bottom of a flower-pot full of soil, it 
will gradually find its way towards the surface, however light 
the soil may be. So it is in sandy soils or subsoils in the open 



SOIL LIABLE TO BE BURNGD UP. 139 

field — all possess a certain power of sucking up water from 
beneath, (p. 118.) If water abound at the depth of a few 
feet, or if it so abound at certain seasons of the year, that 
water will rise towards the surface ; and as the sun's heat 
dries it off by evaporation, more water will follow to supply its 
place. This attraction from beneath will always go on when 
the air is dry and warm, and thus a double evil will ensue — 
the soil will be kept moist and cold, and instead of a constant 
circulation of air doumicards, there will be a constant current 
of water upwards. Thus will the roots, the under soil, and 
the organic matter it contains, be all deprived of the benefits 
which the access of the air is fitted to confer, and both the 
crops and the farmer will suffer in consequence.* The remedy 
for these evils is to be found in an efficient system of drainage. 
6°. It is a curious and apparently a paradoxical observation, 
that draining often improves soils on which the crops are 
liable to be burned up in seasons of drought. Yet, upon a 
little consideration, the fact becomes very intelligible. Let 
, a b he the surface of the soil, and c d the 
level at which the water stagnates, or below 
which there is no outlet by drains or natural 
^ J openings. The roots will readily penetrate 

to c d ; but they will in general refuse to descend farther, 
because of the unwholesome substances which usually collect 
in water that is stagnant. Let a dry season come, and^ their 
roots having little depth, the plants will be more or less speed- 
ily burnt up. And if water ascend from beneath the line c d, 
to moisten the upper soil, it will bring with it those noxious 
substances into which the roots have already refused to pen- 
etrate, and will cause the crop to droop and wither. But put 

* A few miles south of the town of Elgin in Moraysliire, I was shown a 
tract of land on which the crops were usually three weeks later than ou 
another tract, separated from it by a small stream. Beneath the former 
was a pan at the depth of 3 feet, which prevented the surtace-water 
from sinking beyond that level, and thus retarded the growth of the crop. 



140 REMOVAL OF OCHREY MATTER 

in a drain, and lower the level of the water to e f, and the 
rains will wash out the noxious water from the subsoil, and the 
roots will descend deep into it ; so that if a drought again 
come, it may parch the soil above c d, as before, without in- 
juring the plants, since now they are watered and fed by the 
soil beneath, into which the roots have descended. 

^o. In many parts of the country, and especially in the red- 
sandstone districts, the oxide or rust of iron abounds so much 
in the soil, or in the springs which ascend into it, as gradually 
to collect in the subsoil, and form a more or less impervious 
layer or pan, into which the roots cannot penetrate, and 
through which the surface-water refuses to pass. Such soils 
are benefited, for a time, by breaking up the pan where the. 
plough can reach it ; but the pan gradually forms again at a 
greater depth, and the evils again recur. In such cases, the 
insertion of drains below the level of the pan is the most cer- 
tain mode of permanently improving the soil. If the pan be 
now broken up, the rains sink through into the drains, and 
gradually wash out of the soil the iron which would otherwise 
have only sunk to a lower level, and have again formed itself 
into a solid cake. 

8°. It is not less common, even in rich and fertile districts, 
to see crops of beans, or oats, or barley, come up strong and 
healthy, and shoot up even to the time of flowering, and then 
begin k) droop and wither, till at last they more or less com- 
pletely die away. So it is rare in many places to see a second 
year's clover crop come up strong and healthy. These facts 
indicate, in general, the presence of noxious matters in the 
subsoil, which are reached by the roots at an advanced stage 
of their growth, but into which they cannot penetrate without 
injury to the plant. The drain calls in the aid of the rains of 
heaven to wash away these noxious substances from the soil, 
and of the air to change their nature, and this is the most 
likely, as well as the cheapest, means by which these evils can 
be prevented. 



AND OF SALINE INCRUSTATIONS. 141 

9°. Another evil in some countries presents itself to the prac- 
tical farmer. Saline substances are in certain quantity bene- 
ficial, nay, even necessary to the growth of plants. In excess, 
however, they are injurious, and kill many valuable crops. I 
have already adverted to the existence of such saline substances 
in the soil, and to the fact of their rising in incrustations to the 
surface (p. t6) when droughts prevail. 

In some countries, as in the plains of Athens, and near the 
city of Mexico, they come to the surface in such quantity as 
actually to kill the more tender herbage, and to permit only the 
stronger plants to grow. In the plains of Athens, when the 
rainy season ends, a rapid evaporation of water from the surface 
begins. The water, as it rises from beneath, brings much saline 
matter with it. This it leaves behind as it ascends in vapor, 
and thus at length so overloads the surface-soil that tender grass 
refuses to grow, though the stronger wheat plant thrives well 
and comes to maturity. 

This result could scarcely happen if an outlet beneath were 
pronded for the waters which fall during the rainy season. 
These would wash out and carry away the excess of saline mat- 
ter which exists in the under soil, and would thus, when the dry 
weather comes, prevent it from ascending in such quantities as 
to injure the more tender herbage. 

It may be objected to this suggestion, that drains in such 
countries would render more dry a soil already too much parched 
by the hot suns of summer. It is doubtful, however, if this 
would really be the case. Deep drains, as in the case above 
explained, (6°,) would enable the roots to penetrate deeper, and 
would thus render them more independent of the moisture of 
the surface-soil. 

10°. On this subject I shall add one important practical re- 
mark, which will readily suggest itself to the geologist who has 
studied the action of air and water on the various clay-beds 
that occur here and there, as members of the series of stratified 
rocks. There are no clays ivhich do not gradually soften under 



142 DEPTH OF DRAIN'S. 

the united influence of air, of frost, and of running vmter. It is 
false economy, therefore, to lay down tiles of the common horse- shoe 
form without soles, however hard and stiff the clay subsoil may 
appear to be. In the course of ten or fifteen years, the stillest 
clays will generally soften so much as to allow the tile to sink to 
some extent — and many very much sooner. The passage for 
the water is thus gradually narrowed; and when the tile has 
sunk a couple of inches, the whole may have to be taken up. 
Thousands of miles of drains have been thus laid down, both in 
the low country of Scotland and in the southern counties of 
England, which have now become nearly useless. The extend- 
ing use of the pipe-tile will, it is to be hoped, gradually lessen 
the chances of pecuniary loss, which the above practice involves. 

SECTION III. SUMMARY OF THE ECONOMICAL ADVANTAGES OF 

DRAINING. 

The economical advantages of draining in such soils as we 
possess are chiefly these : — 

1. Stiff soils are more easily and more cheaply worked. 

2. Lime and manures have more effect, and go farther. 

3. Seed-time and harvest are earlier and more sure. 

4. Larger crops are reaped, and of better quality. 

5. Valuable crops of wheat and turnips are made to grow 
where scanty crops of oats were formerly the chief return. 

6. Naked fallows are rendered less necessary, and more pro- 
fitable rotations can be introduced. 

7. The climate is improved, and rendered not only more suited 
to the growth of crops, but more favorable to the health of man 
and other animals. 

SECTION IV. OF THE DEPTH TO WHICH DRAINS OUGHT TO BE DUG. 

Much has lately been written in regard to the depth to which 
drains ought to be dug in a system of thorough drainage. It is 



ADVANTAGES OF DRAINING. 143 

diflBcult, perhaps impossible, to establish any empirical or gene- 
ral rule upon this subject; but there are certain indisputable 
points which will serve to guide the intelligent farmer in most 
cases which are likely to occur. 

1°. It is acknowledged, as a general rule, to be of great im- 
portance, that the soil should be deepened — that it should be 
opened up, for the descent of the roots, to the greatest depth to 
which it can be economically done. Now, by the use of the sub- 
soil plough or the fork, the soil can be stirred to a depth of 
from 22 to 24 inches. The tile — or the top of the drain, if made 
of stones — should be at least three inches clear of this disturb- 
ance of the upper soil; and as most tiles will occupy at least 3 
inches, we reach 30 inches as the minimum depth of a tile drain, 
and about 3 feet as the minimum depth of a stone drain, in 
which the layer of stones has a depth of not more than 9 inches. 

2^. Where the outfall is bad, and a depth of 30 or 36 inches 
cannot be obtained, the drains should be made as deep as they 
can be made to run and deliver water. 

3°. The roots of our corn and otlier crops will, in favorable 
circumstances, descend to a depth of 4 or 5 feet. They do so 
in quest of food, and the crop above ground is usually the more 
luxuriant the deeper the roots are enabled to penetrate. It is, 
therefore, theoretically desirable to dry the soil to a greater 
depth even than 3 feet, where it can be done without too great 
an outlay of money. 

4°. The question of economy, therefore, is one of great im- 
portance in this inquiry. In some places it costs as much to 
dig out the fourth or lowest foot as is paid for the upper three ; 
and this additional cost is, in many localities, a valid reason for 
limiting the depth to 30 inches, or 3 feet. 

5°. But the question of economy ought to be disregarded, 
and deeper drains dug where springs occur beneath, or where, 
by going a foot deeper, a bed or layer is reached in which much 
water is present. The reason of this is — that though water 
may not rise from this wet layer in such quantity as actually to 



144 RAINS WARM THE SOIL. 

run along the drains, yet it may do so in sufficient abundance to 
keep the subsoil moist and cold, and thus to retard the develop- 
ment of the crops that grow on its surface. 

The above circumstances appear sufficient to guide the prac- 
tical man in most cases that will present themselves to him. No 
uniform depth can be fixed upon; it must be modified by local 
circumstances. 

In regard to the distance apart at which drains should be 
placed, experience appears to be the only satisfactory guide. 
This says, as yet, that 18 to 21 feet are safe distances, and that 
drains placed at greater distances are doubtful, and may fail to 
dry the land. 

SECTION V. EFFECTS PRODUCED BY THE RAINS AS THEY DESCEND 

THROUGH THE SOIL. 

The most important immediate effect of thorough-drainage 
is, that it enables the rain or other surface water to descend 
more deeply and escape more rapidly from the soil. It maybe 
interesting to specify briefly the benefits which are known to 
follow from this descent of the rain through the soil. 

1°. It causes the air to he renewed. — It is believed that the 
admission of frequently renewed supplies of air into the soil is 
favorable to its fertility. This the descent of the rain pro- 
motes. When it falls upon the soil it makes its way into the 
pores and fissures, expelling of course the air which previously 
filled them. When the rain ceases, the water runs off by the 
drains ; and as it leaves the pores of the soil empty above it, 
the air follows, and fills with a renewed supply the numerous 
cavities from which the descent of the rain had driven it. 
Where land remains full of water, no such renewal of air can 
take place. 

2°. It warms the under soil, — As the rain falls through the 
air it acquires the temperature of the atmosphere. If this be 
higher than that of the surface soil, the latter is warmed byitj 



RAINS WASH OUT NOXIOUS MATTER. 145 

and if the rains be copious, and sink easily into the subsoil, 
they will carry this warmth with them to the depth of the 
drains. Thus the under soil in well drained land is not only 
warmer, because the evaporation is less, but because the rains 
in the summer season actually bring down warmth from the 
heavens to add to their natural heat. 

3°. It equcJises the temperature of the soil during the season of 
growth. — The suii beats upon the surface of the soil, and gra- 
dually warms it. Yet, even in summer, this direct heat descends 
only a few inches beneath the surface. But when rain falls 
upon the warm surface, and finds an easy descent, as it docs in 
open soils," it becomes itself warmer, and carries its heat down 
to the under soil. Then the roots of plants are warmed, and 
general growth is stimulated. 

It has been proved, by experiments with the thermometer, 
that the under as well as the upper soil is warmer in drained 
than in undrained land, and the above are some of the ways by 
which heat seems to be actually added to soils that have been 
thoroughly drained. 

4°. It carries down sohMe substances to the roots of plants. — 
"When rain falls upon heavy undrained land, or upon any land 
into which it does not readily sink, it runs over the surface, dis- 
solves soluble matter, and carries it into the nearest ditch or 
brook. Rain thus robs and impoverishes such land. 

But let it sink where it falls — then whatever it dissolves it 
will carry downwards to the roots — ^it will distribute uniformly 
the saline matters which have a natural tendency to rise to the 
surface, and it will thus promote growth by bringing food every- 
where within the reach of plants. 

5°. It washes noxious 7natters from the under soil. — In the sub- 
soil, beyond the reach of the air, substances are apt to collect, 
especially in red-colored soils, which are injurious to the roots 
of plants. These the descent of the rains alters in part and 
laakes wholesome, and in part washes out. The plough may 
then safely be trusted deeper, and the roots of plants may 
7 



146 PROPORTION OF RAIN EVAPORATED. 

descend in search of food where they wouhl previously have 
been destroyed. 

It is true that, when heavy rains fall, they will also wash out 
of the soil and carry into the drains substances which it would 
be useful to retain. Upon this fact some have laid unnecessary 
stress, and have adduced it as an argument against thorough- 
drainage. But if we balance the constant benefit against the 
occasional evil, I am satisfied, as experience indeed has shown, 
that-the former will greatly preponderate. 

6*^. It hrmgs down fertilising substances from the air. — Besides, 
the rains never descend empty-handed. They constantly bear 
with them gifts, not only of moisture to the parched herbage, 
but of organic and saline food, by which its growth is promoted. 
Ammonia and nitric acid, (p. 33,) together with the many 
exhalations which are daily rising from the earth's surface, 
come down in the rains. ; common salt, gypsum, and other saline 
substances derived from the sea, are rarely wanting ; and thus, 
the constant descent from the heavens may well be supposed to 
counterbalance the occasional washings from the earth. 

I*^. Mitch of the rain is evaporated. — And lastly, in answer to 
this objection, it is of importance to state, that in our climate a 
very large proportion of the rain that falls does not sink through 
the soil, even where there are drains beneath, but rises again 
into the air in the form of watery vapor. Experiments in Man- 
chester have shown, tliat of 31 inches of rain which fall there 
in a year, 24 are evaporated ; while in Yorkshire, of 24| inches 
of rain which fall, only 5 inches run off through pipes laid at «i 
depth of 2 feet 9 inches, the rest being evaporated. There is 
little cause, therefore, for the fear expressed by some, that the 
draining of the land will cause the fertility in any perceptible 
degree to diminish in consequence of the washing of the descend- 
ing rains. They may, as I have said, improve the subsoil by 
washing hurtful substances out of it ; but, in general, the soil 
will have extracted from tlie vvater which filters through it all 
the valuable matter it holds in solution before it has reached the 
depth of a 3-feet drain. 



CHAPTER XL 

Mechanical methods continued. — The subsoil-plough and the fork. — How 
they act in improving the soil. — Experunents on tJie profit of subsoihng. — 
How deep ploughing and trenching improve the soil. — Chemical and 
other effects of common ploughing. — Improvement of the soil by mixing. 

After the land has been laid dry by drains, other mechanical 
modes of improvement can be employed with advantage. Even 
the ordinary methods of mechanical culture become more useful, 
and the benefits which in favorable circumstances are derived 
from turning up the soil are greater and more manifest. These 
facts will appear by a brief consideration of tlie eflects produced 
by ploughing to various depths, and the causes from which they 
arise. 

SECTION I. USE OF THE SUBSOIL-PLOUGH. HOW IT ACTS IN IMPROV- 
ING THE SOIL. 

The subsoil-plough is an auxiliary to the drain — it stirs and 
opens the under soil without mixing it with the upper or imme- 
diately active soil. Though there are few subsoils through 
which the water will not at length make its way, yet there are 
some so stiif, either naturally or from long consolidation, that 
the good effect of a well-arranged line of drains is lessened by 
the slowness with which they allow the superfluous water to pass 
through them. In such cases, the use of the subsoil-plough is most 
advantageous in loosening the under layers of soil, and in allow- 
ing the water to find a ready escape downwards to either side, 
until it reaches the drains.* 

* For a fuller discussion of the benetits of drainage, sec the Author s 
Lectures. 



148 HOW THE SUBSOIL-PLOUGH ACTS. 

It is well known that if a piece of stiff clay be cut into the 
shape of a brick, and then allow^ed to dry, it will contract and 
harden — it will form an air-dried brick, almost impervious to 
any kind of air. Wet it again, it will swell and become still 
more impervious. Cut up while wet, it will only be divided into 
so many pieces, each of which will harden when dry, or the 
whole of which will again attach themselves and stick together 
if exposed to pressure while they are still wet. But tear it 
asunder when dry and it will fall into many pieces, will more or 
less crumble, and. will readily admit the air into its inner parts. 
So it is with a clay subsoil. 

After the land is provided with drains, the subsoil being very 
retentive, the subsoil-plough is used to open it up — to let out 
the water and let in the air. If this is not done, the stiff under 
clay will contract and bake as it dries, but it will neither suffi- 
ciently admit the air, nor open so free a passage for the roots. 
Let this operation, however, be performed when the clay is still 
too wet, a good effect will follow in the first instance ; but after 
a while the cut clay will again cohere, and the farmer will pro- 
nounce subsoiling to be a useless expense o7i his land. Defer 
the use of the subsoil-plough till the clay is dry — it will then 
tear and break instead of cutting it, and its openness will remain. 
Once give the air free access, and, after a time, it so modifies 
the drained clay that it no longer has an equal tendency to 
cohere. 

Mr. Smith of Deanston very judiciously recommended that 
the subsoil-plough should never be used till at least a year after 
the land has been thoroughly drained. This in many cases will 
be a sufficient safeguard — will allow a sufficient time for the 
clay to dry : in other cases, two years may not be too much. 
But this precaution has by some been neglected; and, subsoil- 
ing being with them a failure, they have sought, in some sup- 
posed chemical or other quality of their soil, for the cause of a 
want of success which is to be found in their own neglect of a 
most necessary precaution. Let not the practical man be too 



RESULTS OF EXPERIMENTS. 



149 



hasty in desiring to attain those benefits which attend the adop- 
tion of improved modes of culture ; let him give every method a 
fair trial; and above all, lei him male his trial in the way and 
with the precaution recommended by the author of the method, before 
he pronounces its condemnation. 



SECTION II.- 



-EXPERIMENT ON THE PROFITS OF SUBSOILING. 
USE OF THE FORK. 



The benefits of subsoil ploughing having been sometimes 
called in question, and there being even some cases on record 
in which positive injury has been said to follow from the prac- 
tice, I introduce the following numerical results observed on 
two farms in the neighborhood of Penicuik, a few miles from 
Edinburgh. 

1°. Mr. Wilson of Eastfield, Penicuik, made an experiment, 
after thorough drainage, upon two portions of land under each 
of three crops, and found the effects in the first year after sub- 
soil ploughing, compared with ordinary ploughing, to be as 
follows : 



Ploughed to 8 inches, - 
Subsoiled to 15 inches, 

Difference, 


TURXIPS. 


Bar 

Grain. 


LEY. 

Straw. 


Potatoes. 


tons. cwt. 
20 7 
26 17 


qrs. 

3 


cwt. 
28 
36i 


tons. cwt. 

6 14i 

7 9,^ 


6 10 


i 


8^ 


Voi 

1 



From this table, the effects of subsoiling to a depth of 15, 
above that of ploughing to a depth of 8 inches, appears to have 
been to increase the turnip crop by 6J tons, the potatoes by 15 
cwt., and the barley by 7 bushels of grain and 8 cwt.. of straw. 

2°. Mr. Maclean of Braid wood, near Penicuik, made a sim- 



150 



USE OF DEEP PLOUGHING. 



ilar experiment with turnips and barley, with the following 
results : — 



Ploughed 8 inches deep, - - 
Suhsoiled to 15 inches, - - 

Difference, - - 


Turnips. 


Barley. 


Grain. 


Straw. 


tons. cwt. 
19 15 
23 11 


qrs. 
61 


stones, 
168i 
206^ 


4 2 


1 


38 



The turnip crop, in this experiment, was increased 4 tons ; 
and the barley crop by 6 bushels of grain and 38 stones of 
straw. 

It has been observed, also, that the effects of the subsoiling do 
not cease with the first crop. In one case, in which an accurate 
account of the produce was kept, the profit was estimated at 6s. 
an acre, for Jive successive years after the operation. There is 
reason, therefore, to anticipate general good from the careful 
introduction of this practice ; though it is exceedingly desirable, 
at the same time, that the causes of its failure, wherever it is 
found to fail, should be rigorously investigated. 

The use of the fork, instead of the subsoil-plough, has lately 
been recommended as a more efficient, and even a more econom- 
ical method of opening up the under soil. The upper soil of 9 
to 12 inches is thrown forward with a spade, and the under soil, 
to a depth of 15 inches further, is stirred and turned over with 
a three-pronged fork. I have seen it in operation ; and it cer- 
tainly does appear to loosen and open up the under soil more 
effectually than the subsoil plough can do, and to a depth which 
few subsoil-ploughs are yet able to reach. 



SECTION III. HOW DEEP PLOUGHING AND TRENCHING IMPROVE THE 

SOIL. 

1°. Deep ploughing, like subsoiling, aids the effect of the 



I 



LIME AND CLAY SINK. 151 

drains, and so far — where it goes nearly as deep — even more 
completely effects the same object. But, independently of this, 
it has other uses and merits, and, where it has been successfully 
applied, has im})roved the land by the operation of other causes. 

Subsoiling only lets out the water, and allows access to the 
air and rains, and a free passage to the roots. Deep ploughing, 
in addition to these, brings new earth to the surface, forms thus 
a deeper active soil, and more or less alters both its physical 
qualities and its chemical composition. 

If the plough be made to bring up 2 inches of clay or sand, 
it will stiffen or loosen the soil, as the case may be ; or it may 
affect its color or density. It is clear and simple enough, there- 
fore, that by deep ploughing, the physical properties of the soil 
may be altered. 

But there are certain substances contained in every soil, 
whether in pasture or under the plough, which gradually make 
their way down towards the subsoil. They sink till they reach 
at last that point beyond which the plough does not usually pen- 
etrate. Every farmer knows that lime thus sinks. In peaty 
soils top-dressed with clay, as is done in Lincolnshii*e, the clay 
thus sinks. In sandy, soils, also, which have been clayed, the 
clay sinks : and in all these cases, I beheve, the sinking takes 
place more rapidly when the land is laid down to grass. Where 
soils are marled, the marl sinks ; and the rains, in like manner, 
gradually wash out that which gives their fertilising virtue to 
the large doses of chalk which in some districts, are spread upon 
the land, and render necessary a new application to renovate its 
productive powers. 

If this be the case with earthy substances such as those now 
mentioned, which are, for the most part, insoluble in water, it 
will be readily believed that those saline ingredients of the soil 
which are easily soluble, will be still sooner washed out of the 
upper and conveyed to the under soil.' Thus the subsoil may 
gradually become rich in those substances of which the surface 
soil has been robbed by the rains. Bring up va portion of this 



152 BKIXGIXG UP THE SUBSOIL. 

subsoil by deop-plougliiug, and yon restore to the surface soil a 
part of what it lias beeu gradually losing — you bring up what 
may probably render it more fruitful than before. Such is an 
outline of the reasons in favor of deep ploughing. 

In Germany, theory has pointed out the growing of an occa- 
sional deep-rooted crop in light soils to efiect the same end. The 
deep roots bring up again to the sui'face the substances which 
had naturally sunk. 

But suppose the land to have originally contained something 
noxious to vegetation, which in process of time has been wash- 
ed down into the subsoil, then to bring this again to the sm*- 
face would be materially to injure the land. This also is true, 
and a sound discretion must be employed, in judging when and 
where such evil effects are likely to follow. 

Such cases, however, are more rare than many suppose. 
There are few subsoils which after a year's draining, a full and 
fair exposure to the winter's frost will not in a great degree de- 
prive of all their noxious qualities, and render fit to ameliorate 
the general surface of the poorer lands. If the reader doubt 
this fact, let him visit Tester, and give a calm consideration to 
the effects produced by deep ploughing on the home farm of the 
Marquis of Tweeddale. Let him also study the practice of 
deep ploughing, as it is followed by the Jersey farmers, and ho 
will be still further persuaded of the value of deep-ploughing, 
in some localities at least. 

In many cases the farmer fears, as he does in some parts of 
the county of Durham, to bring up a single inch of the yellow 
clay that lies beneath his surface soil. In the first inch lodges, 
among other substances, the iron worn from his plough, which, 
in some soils, and after a lapse of years, amounts to a conside- 
rable quantity. Till it is exposed to the air, this iron is hurt- 
fid to vegetation ; and one of the benefits of a winter's expo- 
sure of such subsoils to the air arises from the effect produced 
upon the iron they contain. 

It is the want of drainage, however, and of the free access 



COMMON PLOl-GIIIXG. 153 

of air, that most frequently renders snbsoils for a time injurious 
to vegetation. Let the lands be well drained — let the subsoils 
be washed for a few years by the rain water passing through 
them — and there are few of tliose which are clayey in their na- 
ture that may not ultimately be brought to the surface, not 
only with safety, but with advantage to the upper soil. 

2°. Trenching with the spade more fully and effectually per- 
forms what the trench-plough is intended to do. The spade 
more completely turns over the soil than the plough does; and, 
in the hands of an industrious laborer, many think it the more 
economical instrument of the two. 

SECTION IV. CHEMICAL AND OTHER EFFECTS OF COMMON PLOUGHING. 

Other benefits, again, attend upon the ordinary ploughings, 
hoeings, and working of the land. Its parts are more mi- 
nutely divided — the air gets access to every particle — it is ren- 
dered lighter, more open, and more permealjle to the roots. 
The vegetable matter it contains decomposes more rapidly by a 
constant turning of the soil, so that wherever the fibres of the 
roots penetrate, they find organic food provided for them, and 
an abundant supply of the oxygen of the atmosphere to aid in 
preparing it. The production of ammonia and of nitric acid 
also, (see pages 26 to 32,) and the absorption of these and of 
watery vapor from the air, take place to a greater extent the 
finer the soil is pulverised, and the more it has been exposed to 
the action of the atmosphere. All soils contain, likewise, an 
admixture of fragments of those minerals of which the granitic 
and trap rocks are composed, which, by their decay, yield new 
supplies of inorganic food to the growing plant. The more 
frequently they are exposed to the air, the more rapidly do 
these fragments crumble away and decompose. The general 
advantage, indeed, to be derived from tlie constant working of 
the soil, may be inferred from the fact, that Tull reaped 
twelve successive crops of wheat from the same land by the 



154 MIXING THE SOIL 

repeated use of the plough and the horse-hoe. There are few 
soils so stubborn as not to show themselves grateful hi pro- 
portion to the amount of this kind of labor that may be be- 
stowed upon them. 

It is chiefly because the spade or the fork divides and 
separates the soil more completely, or to a greater depth, that 
larger crops have been obtained in many districts by the in- 
troduction of spade husbandry than by the ordinary mode of 
culture with the plough. But all these benefits, which a 
thorough working of the soil is fitted to confer, are only fully 
realised where the land is naturally dry, or by artificial drain- 
age has been freed from superfluous water. 

SECTION V. OF THE IMPROVEMENT OF THE SOIL BY MIXING. 

It has been already shown that the physical properties of 
the soil have an important influence upon its average fertility. 
The admixture of pure sand with clay soils produces an alter- 
ation which is often beneficial, and which is almost wholly 
physical. The sand opens the pores of the clay, and makes it 
more permeable to the air. 

The admixture of clay with sandy or peaty soils, however, 
produces both a physical and a chemical altsiation. . The clay 
not only consolidates and gives body to the sand or peat, but 
it also mixes with them certain earthy and saline substances, 
useful or necessary to the plant, which neither the sand nor 
peat might originally contain in sufficient abundance. It thus 
alters its chemical composition and fits it for nourishing new 
races of plants. 

Such is the case also with admixtures of marl, of shell-sand, 
and of lime. They slightly consolidate the sands and oi>en the 
clays, and thus improve the mechanical texture of both kinds 
of soil ; but their main operation is chemical ; and the almost 
universal benefit they produce depends mainly upon the new 
chemical element they introduce into the soil. 



WITH CLAY, SAND, &C. ] 55 

It is a matter of almost universal remark, that in our cli- 
mate, soils are fertile — clayey or loamy soils, that is — only 
when they contain an appreciable quantity of lime. In what- 
ever way it acts, therefore, the mixing of lime in any of the 
forms above mentioned, with a soil in which little or no lime 
exists, is one of the surest practical methods of bringing it 
nearer in composition to those soils from which the largest 
returns of agricultural produce are usually obtained. Some of 
the chemical effects of lime upon the soil will be explained in a 
subsequent chapter. 



CHAPTER XII. 

Improvement of the soil by planting and the growth of wood. — Influence of 
the Scotch fir and the larch on tlie value of pasture. — Causes of such 
influence of growing trees. — Improvement by laying down to grass. — Ob- 
served flicts. — Forms which the improvement assumes. — In what way 
pastures generally increase in value by age. — Agency of roots, of insects, 
and of winds. — Why rich pasture, wlien ploughed up, is difficult to 
restore. 

There are certain modes of improving tlie soil, which, tliougli 
involving only simple mechanical operations on the part of the 
improver, produce their effects through the agency of refined 
scientific causes. Such are the improvements produced by 
planting and laying down to grass. These, therefore, I shall 
briefly consider in the present chapter. 

SECTION I. IMPROVEMENT OF THE SOIL BY PLANTING, AND HOW 

IT IS EFFECTED. 

It has been observed that lands which are unfit for arable 
culture, and which yield only a trifling rent as natural pasture, 
are yet in many cases capable of growing profitable plantations, 
and of being greatly increased in permanent value by the pro- 
longed growth of wood. Not only, however, do all trees not 
thrive alike on the same soil, but all do not improve the soil on 
which they grow in an equal degree. 

Under the Scotch fir, for example, the pasture which springs 
up after a lapse of years is not worth 6d. more per acre than 
before the land was planted; — under the beech and spruce, it is 
worth even less than before, though the spruce affords excellent 
shelter; — under the ash, it gradually acquires an increased value 



IMPROVEMENT BY PLANTING. 15 1 

of 2s. or 3s. per acre. In oak copses, it becomes worth 5s. or 
6s., but only during the last eight years (of the twenty-four) 
before the oak copse is cut down. But under the larch, after 
the first thirty years, when the thinnings are all cut, land not 
worth originally more than Is. per acre becomes worth 8s. to 
10s. per acre for permanent pasture.* 

1. The main cause of this improvement is to be found in the 
nature of the soil, which gradually accumulates beneath the 
trees by the shedding of their leaves. The shelter from the sun 
and rain which the foliage affords, prevents the vegetable mat- 
ter which falls from being so speedily decomposed, or from 
being so much washed away, and thus permits it to collect in 
larger quantities in a given time than where no such cover ex- 
ists. The more complete the shelter, therefore, the more raj)id 
will the accumulation of soil be, in so far as it depends upon 
this cause. 

2. But the quantity of leaves which annually fall, as well as 
the degree of rapidity with which, under ordinary circumstances, 
they undergo decay, have also much influence upon the extent 
to which the soil is capable of being improved by any given 
species of tree. The broad leaves of the beech and oak decay 
more quickly than the needle-shaped leaves of the pine tribes, 
and this circumstance may assist in rendering the larch more 
valuable as a permanent improver. 

3. We should expect, likewise, that the quantity and quality 
of the inorganic matter contained in the leaves (p. 60) — brought 
up year by year from the roots, and strewed afterwards uni- 
formly over the surface where the leaves are shed — would ma- 
terially affect the value of the soil they form. The dry leaves 
of the oak, for example, contain about 5 per cent of saline and 
earthy matter, while those of the Scotch fir contain less than 2 
per cent; so that, supposing the actual weight of leaves which 
falls from each kiiul of tree to be equal, we should expect a 

* The result of trinls made on the mica slate and gneiss soils (see page 
101) of the Duke of Atholl. 



158 HOW FALLEN LEAVES FERTILIZE. 

greater depth of soil to be formed in the same time by the oak 
than by the Scotch fir. The leaves of the larch in the dry 
state contain from 5 to 6 per cent of saline matter, so that they 
may enrich the surface on which they fall in at least an equal 
degree with those of the oak. Much, however, depends upon 
the annual weight of leaves shed by each kind of tree, in regard 
to which we possess no precise information. 

The improvement of the land, therefore, by the planting of 
trees, depends in part upon the quantity of organic food which 
the trees can extract from the air, and afterwards drop in the 
form of leaves upon the soil, and in part upon the kind and 
quantity of inorganic matter which the roots can bring up from 
beneath, and in like manner strew upon the surface. The quan- 
tity and quality of the latter will, in a great measure, determine 
the kind of grasses which will spring up, and the consequent 
value of the pasture in the feeding of stock. In the larch 
forests of the Duke of Atholl, the most abundant grasses that 
spring up are said to be the Holcus mollis, and the Holcus 
lanatus (the creeping and the meadow soft grasses.) 

The action of a tree, therefore, in improving the soil, is two- 
fold. 

1°. It causes vegetable matter to accumulate on the surface; 
and, 

2°. It brings up from beneath certain substances which are 
of vital importance to the growth of plants, but of which the 
upper soil may have been deficient. 

In a previous chapter I have described the black earth of 
Central Russia, which presents probably the most remarkable 
example now existing of the fertilising effect of a long-con- 
tinued growth of trees. The cotton soil of Central and South- 
ern Hindostan owes its richness to a similar cause. 



LAYING DOWN TO GRASS. 159 



SECTION II. IMPROVEMENT OF THE SOIL BY LAYING DOWN TO GRASS, 

FACTS WHICH HAVE BEEN ASCERTAINED. 

On this subject, two facts seem to be pretty generally 
acknowledged. 

First, That land laid down to artificial grasses for one, two, 
three, or more years, is in some degree rested or recruited, and 
is fitted for the better production of after crops of corn. 
Letting it lie a year or two longer in grass, therefore, is one of 
the received modes of bringing back to a sound condition 
a soil that has been exhausted by injudicious cropping. 

Second, That land thus laid down with artificial grasses 
diminishes in value again after two, three, or five years — more 
or less — and only by slow degrees acquires a thick sward of 
rich, nourishing natural herbage. Hence the opinion that grass 
land improves in quality the longer it is permitted to lie — the 
unwillingness to plough up old pasture — and the comparatively 
high rents which, in some parts of the country, old grass land is 
known to yield. 

Granting that grass land does thus generally increase in value, 
three important facts must be borne in mind before we attempt 
to assign the cause of this improvement, or the circumstances 
under which it is likely to take place for the longest time and to 
the greatest extent. 

1. The value of the grass in any given spot may increase for 
au indefinite period, but it will never improve beyond a certain 
extent — it will necessarily be limited, as all other crops are, by 
the quality of the land. Hence the mere laying down to grass 
will not make all land good, however long it may lie. The ex- 
tensive commons, heaths, and wastes, which have been in grass 
from the most remote times, are evidence of this. They have, 
in most cases, yielded so poor a natural herbage as to have 
been considered unworthy of being enclosed as permanent pas- 
ture. 



160 NATURE OF THE IMPROVEMENT. 

2. Some grass-lands will retain the good condition they thus 
slowly acquire for a very long period, and without manuring — in 
the same way, and upon nearly the same principle, that some rich 
corn-lands have yielded successive crops for 100 years without 
manure. The rich grass-lands of England, and especially of 
Ireland, many of which have been in pasture from time imme- 
morial, without receiving any known return for all they have 
yielded, are illustrations of this fact. 

3. But others, if grazed, cropped with sheep, or cut for hay, 
will gradually deteriorate, unless some proper supply of manure 
be given to them — which required supply must vary with the 
nature of the soil, with the kind of stock fed upon it, and with 
the kind of treatment to which it has been subjected. 

SECTION III. FORM WHICH THE IMPROVEMENT ASSUMES, AND HOW 

IT IS BROUGHT ABOUT. 

In regard to the acknowledged benefit of laying down to grass, 
then, two points require consideration. 

1°. What form does it assume — and how is it effected ? 

The improvement takes place by the gradual accmnulation 
of a dark-brown soil rich in vegetable matter, which soil thick- 
ens or deepens in proportion to the time during which it is 
allowed to lie in grass. It is a law of nature, that this accu- 
mulation takes place more rapidly in the temperate than in 
tropical climates, and it would appear as if the consequent 
darkening of the soil were intended, among other purposes, to 
enable it to absorb more of the sun's warmth, and thus more 
speedily to bring forward vegetation where the average tempe- 
rature is low and the summers comparatively short. 

If the soil be very light and sandy, the thickening of the 
vegetable matter is sooner arrested ; if it be moderately heavy 
laud, the improvement continues for a longer period; and some 
of the heaviest clays in England are known to bear the richest 
permanent pastures. 



HOW IT IS BROUGHT ABOUT. 161 

The soils formed on the surface of all our rich old pasture 
lands thus come to possess a remarkable degree of uniformity 
• — both in physical character and in chemical composition. 
This uniformity they gradually acquire, even upon the stiff clays 
of the lias and Oxford clay, which originally, no doubt, have 
been left to natural pasture — as many clay lands still are — 
from the difficulty and expense of submitting them to arable 
culture. 

2°. How do they acquire this new character, and why is it 
the work of so much time ? 

a. When the young grass throws up its leaves into the air, 
from which it derives so much of its nourishment, it throws 
down its roots into the soil in quest of food of another kind. 
The leaves may be mown or cropped by animals, and carried 
off the field ; but the roots remain in the soil, and, as they die, 
gradually fill its upper part with vegetable matter. On an 
average, the annual production of roots on old grass-land is 
equal to one-third or one-fourth of the weight of hay carried 
off* — though no doubt it varies much, both with the kind of 
grass and with the kind of soil. When wheat is cut down, the 
quantity of straw left in the field, in the form of stubble and 
roots, is sometimes greater than the quantity candied off in the 
sheaf. Upon a grass field two or three tons of hay may be 
reaped from an acre, and therefore, from half a ton to a ton of 
dry roots is annually produced and left in the soil. If anything 
like this weight of roots die every year, in land kept in pasture, 
we can readily understand how the vegetable matter in the soil 
should gradually accumulate. In arable land this accumulation 
is prevented by the constant turning up of the soil, by which 
the fibrous roots, being exposed to the free access of air and 
moisture, are made to undergo a more rapid decomposition. 

h. But the roots and leaves of the grasses contain earthy 
and saline matters also. Dry hay leaves from an eighth to a 

* See the Autlior's Lectures on Agricultural Chemistry and Geology, 2d 
edition. 



162 CIRCUMSTANCES BY WHICH IT IS PROMOTED. 

tenth part of its weight of ash when burned. Along with the 
dead vegetable matter of the soil, this inorganic matter also 
accumulates in the form of an exceedingly fine earthy povrder; 
hence one cause of the universal fineness of the surface-mould 
of old grass-fields. The earthy portion of this inorganic mat- 
ter consists chiefly of silica, hme, and magnesia, with scarcely 
a trace of alumina ; so that, even on the stiffest clays, a sur- 
face soil may be ultimately formed, in which the quantity of 
alumina — the substance of clay — is comparatively small. 

c. There are still other agencies at work, by which the sur- 
face of stiff soils is made to undergo a change. As the roots of 
the grasses penetrate into the clay, they more or less open up a 
way into it for the rains. Now, the rains in nearly all lands, 
when they have a passage downwards, have a tendency to carry 
down the clay along with them. They do so, it has been ob- 
served, on sandy and peaty soils, and more quickly when these 
soils are laid down to grass. Hence the mechanical action of 
the rains — slowly in many localities, yet surely — has a tendency 
to lighten the surface soil, by removing a portion of its clay. 
They constitute one of those natural agencies by which, as 
elsewhere explained, important differences are ultimately estab- 
lished, almost everywhere, between the surface crop-bearing 
soil and the subsoil on which it rests. 

d. But further, the heats of summer and the frosts of winter 
aid this slow alteration. In the extremes of heat and of cold, 
the soil contracts more than the roots of the grasses do ; and 
similar, though less visible, differences lake place during the 
striking changes of temperature which are experienced in our 
climate in the different parts of almost every day. When the 
rain falls, also, on the parched field, or when a thaw comes on 
in winter, the earth expands, while the roots of the grasses re- 
main nearly fixed ; hence the soil rises up among the leaves, 
mixes with the vegetable matter, and thus assists in the slow 
accumulation of a rich vegetable mould. 

The reader may have witnessed in winter hoAv, on a field or 



EFFECT OF EARTH-WORMS AND WINDS. 163 

by a way-side, the earth rises above the stones, and appears in- 
clined to cover them ; he may even have seen, in a deserted 
and undisturbed highway, the stones gradually sinking and dis- 
appearing altogether, when the repetition of this altei'nate 
contraction and expansion of the soil for a succession of winters 
has increased, in a great degree, the effects which follow from a 
single accession of frosty weather. 

So it is in the fields. And if a person skilled in the soils of 
a given district can make a guess at the time when a given 
field was laid down to grass, by the depth at which the stones 
are found beneath the surface, it is partly because this loosen- 
ing and expansion of the soil, while the stones remain fixed, 
tends to throw the latter down by an almost imperceptible 
quantity every year that passes. 

e. Such movements as these act in opening up the surface 
soil, in mixing it with the decaying vegetable matter, and in 
allowing the slow action of the rains gradually to give its 
earthy portion a lighter character. But with these, among 
other causes, conspires also the action of living animals. Few 
persons have followed the plough without occasionally observ- 
ing the vast quantities of earth-worms with which some fields 
seem to be filled. On a close-shaven lawn, many have noticed 
the frequent little heaps of earth which these worms during 
the night have thrown out upon the grass. These and other 
minute animals are continually at work, especially beneath an 
undisturbed and grassy sward — and they nightly bring up from 
a considerable depth, and discharge on the surface, their bur- 
den of fine fertilising loamy earth. Each of these burdens is 
an actual gain to the rich surface soil; and who can doubt 
that, in the lapse of years, the unseen and unappreciated 
labors of these insect tribes must both materially improve its 
quality and increase its depth ? * 

* In the Prize Essays of the Highland Society, (vol. 1. p. 191,) the reader 
will find the testimony of a practical man that such was in reality the case, 
as observed by himself on part of his own farm in Koxburgshire. 



164 FOREST TREES ENRICH THE SOIL. 

/. In most localities, also, the winds may be mentioned among 
the natural agencies by which the soil on grass lands is slowly 
imi^roved. They seldom sweep over any considerable extent of 
arable land without bearing with them particles of dust and 
sand, which they drop in sheltered places, or leave behind them 
when sifted by the blades of grass, or by the leaves of an ex- 
tensive forest. In hot summers, in dry springs, and even in 
winter, when the snow is drifting, the ploughed lands and dusty 
roads are more or less bared of their lighter particles of soil, 
which are strewed by the winds as a natural top-dressing over 
the neighboring untilled fields. 

In some countries the agency of the winds is more conspicuous 
than among ourselves. Thus on the banks of the Kuruman and 
Orange rivers in South Africa, the winds blow during the spring 
months — August to November in that climate — from the Kula- 
gare desert, bearing with them light particles of dust, which 
make the air seem as if dense with smoke, and which are so ex- 
quisitely fine as to penetrate through seams and cracks which 
are almost impervious to water.* Forest trees and waving 
grass sift this thick air and enrich the soils on which they grow 
by the earthy particles they arrest. 

In countries where active volcanoes exist, these also exercise 
an appreciable influence of a similar kind upon the surface soil. 
Showers of dust and ashes are sprinkled widely over the land, 
by which its natural agricultural capabilities are materially in- 
terfered with. Vesuvius is said, in this way, to scatter its ashes 
over the adjoining country, so as, on an average, to destroy the 
crop every eighth year. But to this circumstance the remarka- 

I have lately seen a notice from the Carlisle Journal of a bowhng-green 
at Penrith, (45 yards by 32,) from which, after watering with a solution of 
corrosive sublimate, eleven stones of worms were this year gathered, and 
four years ago ticenty stones. The labors of such a number of animals must 
produce in time a very sensible effect. 

* Mojfafs Missionary Labors, p. 333. 



ALL LAND REQUIRES ADDITIONS. 165 

ble general richness of the soil is ascribed — (Moiil.) So does 
good arise from seeming evil. 

There are natural causes, then, which we knoio to be at work, 
that are sufficient to account for nearly all the facts that have 
been observed in regard to the effect of laying land down to 
grass. Stiff clays will gradually become lighter on the surface, 
and, if the subsoil be rich in all the kinds of inorganic food 
which the grasses- require, will go on improving for an indefinite 
period without the aid of manure. Let them, however, be de- 
ficient in, or let them gradually become exhausted of any one 
kind of this food, and the grass lands will either gradually-dete- 
riorate after they have reached a certain degree of excellence, 
or they must be supplied with that one ingredient, that one kind 
of manure of which they stand in need. It is doubtful if any 
pasture lands are so naturally rich as to bear to be cropped for 
centuries without the addition of manure, and at the same time 
without deterioration. Where they appear to be so, they pro- 
bably receive from springs, from sea-drift, or from some other 
unobserved source, those perennial supplies which reason pro- 
nounces to be indispensable. 

On soils that are light, again — which naturally contain little 
clay — the grasses will thrive more rapidly, and a thick sward 
will be sooner formed, but the tendency of rains to wash out the 
clay may prevent them from ever attaining that luxuriance which 
is observed upon the old pastures of the clay lands. 

On undrained heaths and commons, and generally on any soil 
which is deficient in some fertilising element, neither abundant 
herbage, nor good crops of any other kind, can be expected to 
flourish. Laying such lands down, or permitting them to remain 
in grass, may prepare them for by-and-by yielding one or two 
average crops of corn, but cannot be expected alone to convert 
them into valuable pasture. 

Finally, plough up the old pastures on the surface of which 
this light and most favorable soil has been long accumulating, 
and the heavy soil from beneath will be again mixed up with it, 



166 NATURAL GRASSES CHANGE. 

the vegetable matter will disappear rapidly by exposure to the 
air during the frequent ploughings; and, if again laid down to 
grass, the slow changes of many years must again be begun 
through the agency of the same natural causes, before it become 
capable a second time of bearing the same rich herbage it was 
known to nourish while it lay undisturbed. 

Many have supposed that, by sowing down with the natural 
grasses, a thick and permanent sward may at once be obtained; 
and on light loamy land, rich in vegetable matters, this method 
may, to a certain extent, succeed ; but, on heavy land, in which 
stiff -clay abounds and vegetable matter is defective, disappoint- 
ment will often fallow the sowing of the most carefully selected 
seeds. By the agency, among other causes, of those above 
adverted to, the soil gradually changes, so that it is unfit, when 
first laid down, to bear those grasses which, ten or twenty years 
afterwards, will spontaneously and luxuriantly grow upon it. 
Nature is not regulated by one principle in the growth of corn 
and by another in growing grass ; the apparent difference in her 
procedure arises from real differences in our j^ractice. 



CHAPTER XIII. 

Chemical methods of improving the soil. — Use of manures. — Objects of the 
farmer. — Vegetable manures. — Green manuring. — Use of sea- weed. — Dry- 
vegetable substances. — Straw. — Sawdust. — Bran. — Brewers' grains. — 
Malt-dust. — Rape-dust. — Hemp, poppy, cotton, and cocoa-nut cakes. — Use 
of peat. — Peat composts and tanners' bark. — Use of vegetable substances 
decomposed by art. — Charred peat, wood charcoal, soot, coal-dust, and 
coal-tar. — Relative fertilising and money values of different vegetable 
manures. 

KoNE of the methods of improving the soil which have been 
described in the preceding chapter are purely mechanical. They 
all involve, as I have shown, some chemical alterations also, 
which are to be explained only by a knowledge of chemical 
principles. But the manuring of the land is more strictly a 
chemical operation, and may therefore with propriety be sepa- 
rated from those methods of improvement which involve at the 
same time important and expensive mechanical operations. 

In commencing the tillage of a piece of land, the conscien- 
tious farmer may have three objects in view in regard to it. 

1. He may wish to reclaim a waste, or to restore a neglected 
farm to an average condition of fertility. 

2. Finding the land in this average state, his utmost ambition 
may be to keep it in its present condition; or, 

3. By high farming he may wish to develop all its capabili- 
ties, and to increase its permanent productiveness in the great- 
est possible degree. 

The man who aims at the last of these objects is not only the 
best tenant and the best citizen, but he is also his own best 



168 "WHAT IS A MANURE. 

friend. The highest farming, skilfully and prudently conduct- 
ed, is also the most remunerntinp:.* 

But whichever of these throe ends he aims at, he will be un- 
able to attain it without a due knowledge of the various 
manures it may be in his power to apply to his land — what 
these manures are, or of what they consist — the general and 
special purposes they are. each fitted or intended to serve — 
wiiich are the most effective for this or that crop, and why 
they are so — how they are to be obtained in the greatest 
abundance, and at the least cost^how their strength may be 
economised — and in what state and at what season of the year 
they may be most beneficially applied to the land. Such are a 
few of the questions which the skilful farmer should be ready 
to ask himself, and should be able to answer. 

By a manure is to be understood whatever is capable of 
feeding or of supplying food to the plant. And as plants re- 
quire earthy and saline as well as vegetable food, gypsum and 
nitrate of soda are as properly called manures as farmyard 
dung, bone-dust, or nightsoil. 

Manures naturally divide themselves into such as are of vege- 
tahle, of animal, and of mineral origin. I shall consider these 
different kinds of manure in successive chapters. 

SECTION I. OF THE USE OF VEGETABLE MANURES. 

There are two purposes which vegetable manure is generally 

* A singular illustration of this fact is mentioned as observed in Hol- 
stein, where marl is extensively applied to the land. Those fields which 
nre marled yield a much larger produce than before, while the adjoining 
fields, which are left unmarled, give a less return than when all were un- 
maiied ; so that the holder of the latter is compelled to improve by marl- 
ing his fields also. — Sprengel. 

It is also a curious but important observation, that when light lauds, 
poor in vegetable matter, are reclaimed from a state of waste, they pay 
better for the manure added to them every succeeding year ; that is, the 
richer in organic matter they become. — Yon Vogiit. 



VEGETABLE MANURES. 169 

supposed to serve when added to the soil — it loosens the land, 
opens its pores, and makes it lighter ; and it also supplies 
organic food to the roots of the growing plant. It serves, how- 
ever, a third purpose. It yields to the roots those saline and 
earthy matters, which it is their duty to find in the soil, and 
which exist in decaying plants in a state more peculiarly fitted 
to enter readily into the circulating system of new races. 

Decayed vegetable matters, therefore, are in reality mixed 
manures, and their value in enriching the land must vary con- 
siderably with the kind of plants, and with the parts of those 
plants of which they are chiefly made up. This depends upon 
the remarkable difference which exists in the quantity arid kind 
of the inorganic matter contained in different vegetable sub- 
stances, as indicated by the ash they leave, (see pages 59 to 
69.) Thus if 1000 lb. of the sawdust of the willow be fer- 
mented and added to the soil, they will enrich it by the addi- 
tion of only 4| lb. of saline and earthy matter, while 1000 lb. 
of the dry leaves of the same tree, fermented and laid on, will 
add 82 lb. of inorganic matter. Thus, independent of the 
effect of the organic matter in each, the one will produce a 
very much greater effect upon the soil than the other.* 

There are several states in which vegetable matter is collect- 
ed by the husbandman for the purpose of being applied to the 
land — such as the green state, the dry state, that state of im- 
perfect natural decay in which it forms ;peat, and the decom- 
posed state of charcoal, &c., to which it has been reduced by 
art. 

SECTION II. OF GREEN MANURING, AND OF THE USE OF SEA-WEED. 

When grass is mown in the field, and laid in heaps, it speed- 

* It is owing, in part, to this large quantity of saline and other inorganic 
matters which they contain, that fermented leaves alone form too strong a 
dressing for flower borders, and that gardeners therefore generally mix them 
up into a compost. 

8 



1^0 GREEN MANURING. 

ily heats, ferments, and rots. But, if turned over frequently and 
dried into hay, it may be kept for a great length of time without 
undergoing any material alteration. The same is true of all 
other vegetable substances — they all rot more readily in the 
green state. The reason of this is, that the sap or juice of the 
goeen plant begins very soon to ferment in the interior of the 
stem and leaves, and speedily communicates the same condition 
to the moist fibre of the plant itself. When once it has been 
dried, the vegetable matter of the sap loses this easy tendency 
to decay, and thus admits of long preservation. 

The same rapid decay of green vegetable matter takes place 
when it is buried in the soil. Hence the cleanings and scour- 
ings of the ditches and hedge-sides form a compost of mixed 
earth and fresh vegetable matter, wdiich soon becomes capable 
of enriching the ground. When a green crop is ploughed into 
a field, the whole of its surface is converted into such a compost 
— the vegetable matter in a short time decays into a light, 
black mould, and enriches in a remarkable degree, and fertilises 
the soil. 

This is one reason why the success of wheat after clover, or 
of oats after lea, depends so much on the ground being w^ell 
covered when first ploughed up. 

1°. Green manuring. — Hence the practice of green manuring 
has been in use from very early periods. The second or third 
crop of lucerne vv^as ploughed in by the ancient Romans — as it 
still is by the modern Italians. In Tuscany, the ichite lupm is 
i;)loughed in — in parts of France, the bean and the vetch — in 
Germany, borage — and upon sandy soils in Holstein, slurry. 
The Madia sativa has lately been tried as a green manure in 
Silesia. It is sown in June, and is ploughed in, when two feet 
high, in October. Sheep do not eat it ; so that if a flock of 
sheep be turned in, they eat up the weeds and trample down the 
madia, after which it is easily ploughed in. In a month it is 
rotten, and the land may be cross-ploughed, and the winter corn 
sown. 



TURNIP LEAVES AND POTATO TOPS READILY DECAY. Ill 

In French Flanders, two crops of clover are cut, and the third 
is ploughed in. In some parts of the United States, the clover 
is never cut, but is ploughed in as the only manure ; in other 
parts, the first crop is cut and the second ploughed in. In some 
of the northern States, Indian corn is sown upon poor lands, at 
the rate of 4 to 6 bushels an acre, and two or sometimes three 
such crops are turned in during the summer. In north-eastern 
China, a species of coronilla and a trefoil are specially sown and 
grown in ridges, as a manure for the rice crop. They are 
ploughed and harrowed in before the young rice plants are put 
into the flooded land. 

In Sussex, and in parts of Scotland, hirmp seed has been 
sown at the end of harvest, and after two months again ploughed 
in, with great benefit to the land. Wild mustard, also, which 
grows so abundantly as a weed on many of our corn-fields, is 
not unfrequently raised for ploughing in green. White mustard 
is sown in Norfolk, and ploughed in as a preparation for wheat ; 
sometimes, also, on the stubble, as a preparation for turnips. It 
is said to destroy the wire-worm. Turnip leaves and potato tops 
decay more readily and more perfectly, and are more enriching 
when buried in the green state. It is a prudent economy, there- 
fore, where circumstances admit of it, to bury the potato tops 
on the spot from which the potatoes are raised.* Since the 
time of the Romans, it has been the custom to bury the cut- 
tings of the vine stocks at the roots of the vines themselves ; 
and many vineyards flourish for a succession of years without 
any other manuring. In the Weald of Kent the prunings of 
the hop-vine, chopped and dug in, or made into a compost and 
applied to the roots of the hop, give a larger crop, and with 
half the manure, than when they are burned or thrown away, 
as is usually done. 

* By taking- off the blossoms of potatoes — besides the usual increase of 
crop — the tops keep green till the potatoes are lifted. Thus much green 
matter is obtained : and if this be made mto manure, and applied to the 
next potato crop, it is said to raise the largest xnoduce of tubers. 



Its USE OF SEA-WEED. 

Buckwheat, rye, winter tares, clover, and rape, are all occa- 
sionally sown in tliis country for the purpose of being ploughed 
in. This should be done when thefiower has just begun to open, 
and, if possible, at a season when the warmth of the air and the 
dryness of the soil are such as to facilitate decomposition. 

That the soil should be richer in vegetable matter after this 
burial of a crop than it was before the seed of that crop was 
sown, and should also be otherwise benefited, will be understood 
by recollecting (see page 36) that perhaps three-fourths of the 
whole organic matter we bury has been derived from the air — 
that by this process of ploughing in, the vegetable matter is 
more equally diffused through the whole soil, than it could ever 
be by any merely mechanical means — and that by the natural 
decay of this vegetable matter, ammonia and nitric acid are, to 
a greater extent, (page 26 and 29,) produced in the soil, and 
its agricultural capabilities in consequence materially increased. 
Indeed, a green crop ploughed in is believed, by some practical men, 
to enrich the soil as much as the droppings of cattle from a quantity 
of green food three times as great. 

These considerations, while they explain the effect and illus- 
trate the value of green manuring, will also satisfy the intelligent 
agriculturist that there exist methods of improving his land 
without the aid either of town or of foreign manures — and that 
he overlooks an important natural means of wealth who neglects 
the green sods and the crops of weeds that flourish by his hedge- 
rows and ditches. Left to themselves, they will ripen their 
seeds, and sow them annually in his fields ; collected in compost 
heaps, they will materially add to his yearly crops of corn. 

2°. Use of sea-weed. — Among green manures, the use of fresh 
sea-ware deserves especial mention, from the remarkably fertilis- 
ing properties it is known to possess, as well as from the great 
extent to which it is employed on all our coasts. The agricul- 
tural produce of the Isle of Thanet, in Kent, is said to have 
been doubled or tripled by the use of this manure; the farms on 
the Lothian coasts let for 20s. or oOs. more rent per acre when 



SPECIAL ACTION OF SEA-WEED. 173 

they have a right of way to the sea, where the weed is thrown 
ashore;* and in the Western Isles the sea-ware, the shell-marl, 
and the peat-ash, are the three great natural fertilisers, to which 
the "agriculture of this remote region is indebted for the com- 
parative prosperity to which it has in some of the islands already 
attained. 

The common red tangle, which grows farther out at sea, is in 
some districts preferred as a manure to the other varieties of 
sea-weed, when applied green or made into compost. At Oban, 
on the west coast of Scotland, the fishermen bring it in their 
boats and sell it on the shore at a shilling a cart. One cart is 
there reckoned equal to two of farmyard dung for raising pota- 
toes. Used alone for this crop, it gives a good return, but gen- 
erally of inferior quality.f On the south-east coast of Fife, 
where the sea-weed is laid on the stubble at the rate of 20 carts 
an imperial acre, ploughed in, and the turnips afterwards raised 
with half dung, the clover is said never to fail. Laid on bean- 
stubble, and ploughed in, 2t cart-loads gave in Suffolk, (1819,) 
three times as much wheat as 5 bushels of salt and 15 loads of 
farmyard manure per acre. 

Sea-weeds decompose with great ease when collected in heaps 
or spread upon the land. During their decay they yield not 
only organic food to the plant, but saline matters also, to which 
much of their efficacy both on the grass and the corn crops is 
no doubt to be ascribed. 

Especially to this saline matter may be ascribed the benefi- 
cial influence of sea-weed on garden asparagus, originally a sea- 
side plant, and upon fruits like raspberries, which contain much 
alkaline matter. 

* In this locality 16 loads of sea-weed are reckoned equal to 20 tons of 
farmyard manure. In the Island of Lewis 20 tons of sea- ware, which would 
yield half a ton of Icelp, are considered to be ample manure (or a Scotch acre. 

f The potatoes are said to be of better quality when the sea-weed is put 
into the soil and covered with a layer of eartli, upon which the potatoes are 
to be planted. 



174 DRY VEGETABLE MATTER FOR MANURING. 

The value of sea-weed as a manure may be understood from 
the fact that the fticus saccharimis leaves, when dry, 28-6 per 
cent of ash, and contains 19 '2 6 — say 20 per cent — of protein 
compounds. In its recent state it contains 1 6 per cent of water, 
(Payen.) 

section iii. of manuring with dry vegetable matter. 

1. Straw, — Almost every one knows that the sawdust of most 
common woods decays very slowly — so slowly, that it is rare to 
meet with a practical farmer who considers it worth the trouble 
to mix sawdust with his composts. This property of slow decay 
is possessed in a certain degree by all dry vegetable matter. 
Heaps of dry straw when alone, or even when mixed with 
earth, will ferment with comparative difficulty, and with great 
slowness. It is necessary, therefore, to mix it, as is usually 
done, with some substance that ferments more readily, and 
which will impart its own fermenting state to the straw. Ani- 
mal matters of any kind, such as the urine and droppings of 
cattle, are of this character ; and it is by admixture with these 
that the straw which is trodden down in the farmyard is m.ade 
to undergo a more or less rapid fermentation. 

The object of this fermentation is twofold — first, to reduce the 
particles of the straw to such a minute state of division, that 
they may admit of being diffused through the soil ; and second, 
that the dry vegetable matter may be so changed by exposure 
to the air and other agencies, as to be fitted to yield without 
difficulty both organic and inorganic food to the roots of the 
plants it is intended to nourish. 

Differences of opinion have prevailed, and discussions have 
taken place, as to the relative efficacy of long and short, or of 
half fermented and of fully rotten dung. But if it be added 
soldy for the purpose of yielding food to the plant, or of prepar- 
ing food for it, the case is very simple. The more complete the 
state of fermentation, if not carried too far, the more immediate 



LOSS OF WEIGHT BY FERMENTATION. 1T5 

will be the agency of the manure — hence the propriety of the 
application of short dung to turnips and other plants it is desir- 
able to bring rapidly forward ; but if the manure be only half 
decayed, it will require time in the soil to complete the decom- 
position, so that its action will be more gradual and prolonged. 

Though in the latter case the immediate action is not so per- 
ceptible, yet the ultimate benefit to the soil, and to the crops, 
may be even greater, supposing them to be such as require no 
special forcing at one period of the year. This is easily under- 
stood. While it is undergoing fermentation in the farmyard, 
the straw loses part of its substance — either in the state of 
gaseous matter, which escapes into the air — or of saline matter, 
which is washed out in the liquid form. Thus, after complete 
fermentation, the quantity of matter present is really less, and 
consequently, when added to the soil, though the immediate 
effect upon the crop be greater, the whole effect may also bo 
very considerably less. 

This will appear more clearly when it is considered that the 
quantity of recent dung — mixed straw and cow dung — is by 
experiment equal on an average to 2 or 2^ times that of the 
dry food and fodder taken together, while, when fully rotten, 
the weight of the dung may be no greater than that of the dry 
food and fodder consumed by the cattle. 

Thus it has been found that one ton (20 cwt.) of dry food 
and straw gives a quantity of farmyard dung which weighs, 



"When recent, 


46 to 50 cwt. 


After 6 weeks, 


40 to 44 . . 


After 8 weeksj 


38 to 40 . . 


When lialf rotten, 


30 to 35 . . 


When fully rotten. 


20 to 25 .. 



A part of this loss may, no doubt, be ascribed to the evapora,- 
tion of a portion of the water of the recent dung ; but the 
larger part is due to an actual escape of the substance of the 
manure itself. The farmer, therefore, who applies the manure 
from a given weight of food and straw, in a fresh state, adds 



116 SAWDUST AND BRAN. 

more to his land than if he first allows it to become perfectly 
fermented. Were he to chop his straw, and put it in as it 
comes fresh from the field, he would add still more ; but its ac- 
tion as a manure would be slower, and while it would benefi- 
cially open stiff and heavy soils, it would injure others, by 
rendering them too light and porous, 

2. Sawdust. — With a view to this slow amelioration, dry 
vegetable matter of any kind may, if in a sufficient state of di- 
vision, be added with benefit to the soil. Even sawdust, 
applied largely to the land, has been found to improve it, — 
little at first, more during the second year after it was applied, 
still more during the third, and most of all in the fourth season 
after it was mixed with the soil. That any dry vegetable mat- 
ter, therefore, does not produce an immediate effect, ought not 
to induce the practical farmer to despise the application to his 
land — either alone or in the form of a compost — of everything 
of the kind he can readily obtain. If his fields are not already 
very rich in vegetable matter, both he and they will be ulti- 
mately benefited by such^ additions to the soil. 

Saturated with ammoniacal liquor, or with hquid manure, 
sawdust has been profitably used, and without further addition, 
in the raising of turnips. It may also be charred either by 
burning, or by alternate layers of quick-lime, and thus benefi- 
cially applied. 

3. Bran. — The bran and pollard of wheat are highly recom- 
mended as manures. Drilled in with the turnip seed at the rate 
of 5 or 6 cwt. an acre, at a- cost of £1 2s. 6d., it brought the 
young plants rapidly forward, and gave one-third more in 
weight of bulbs than the other parts of the field, which had 
been treated in the same way in every respect, except that no 
addition of bran had been made to them. If moistened with 
urine and slightly fermented, the action of bran would no 
doubt be hastened and rendered more powerful. 

The husk of the oat, hitherto wast(M at many of the oatmeal 



MALT AND RAPE DUST. 17t 

mills in the north, might also be beneficially fennented and em- 
ployed as a manure. 

4. Brewers' grains, though usually given as food to fattening 
cattle or to milch cows, are by some of the farmers in Norfolk 
employed as a manure. They are supposed to pay best when 
mixed with farmyard manure. 

5. Malt-dust — cummins, or combings — consists of the dried 
sprouts of barley, which, when the sprouted seed is dried in the 
process of malting, break off and form a coarse powder. This 
is found to be almost equal to rape-dust in fertilising power. 
One hundred bushels of barley yield 105 to 110 of malt and 4 
to 5 of dust. In this neighborhood (Durham) it is sold at one 
shilling a bushel. 

Applied in the dry state, malt-dust decomposes slowly, and 
from its extreme lightness is applied with difficulty, as a top- 
dressing. If it be moistened with liquid manure and laid in 
heaps for a few days till it heat and begin to ferment, it may 
be used either as a top-dressing for grass, clover, and young 
corn, or it may be drilled in with the seed. It may also in this 
state be employed with advantage without any other manure 
for the turnip or potato crop ; but the turnip-seed should not be 
brought into immediate contact with it in the drills. 

Malt-dust leaves, when dry, 8 per cent of ash, and contains 
23 per cent of protein compounds, (Payen.) This composition 
explains both its fertilising action when applied to the soil, and 
its nourishing effects when given to cattle or sheep along with 
turnips. 

6. Rape-diist. — It is from the straw of the corn-bearing plants, 
or from the stems and leaves of the grasses, that the largest 
portion of the strictly vegetable manures applied to the soil is 
generally obtained or prepared. But the seeds of all plants are 
much more enriching than the substance of their leaves and 
stems. These seeds, however, are in general too va'uable for 
food to admit of their application as a manure. Still the re- 
fuse of some — as that of different kinds of rape-seed after the 

8* 



118 HEMP, POPPY, AND COTTON CAKES. 

oil is expressed, and which is unpalatable to cattle — ^is applied 
with great benefit to the land. Drilled in with the winter or 
spring wheat, or scattered as a top-dressing in spring at the 
rate of 5 cwt. an acre, it gives a largely increased and remune- 
rating return. Applied at a cost of 40s. per acre to wheat, it 
has been known to increase the produce 10 bushels an acre 
(from 29 to 39 bushels) and to give one-fifth more straw. Nor 
is the practice recent, for the application of it in this way, and 
at a cost of 40s to 42s. an acre, was common in Norfolk in the 
time of Arthur Young, (1170,) eighty years ago. 

In some districts it is used largely, and without admixture, 
for the raising of turnips. It is applied with equal success to 
the cultivation of potatoes, if it be put in the place of a part 
only of the manure. If used alone it is apt to give very large 
and luxuriant tops, with only an inferior weight of tubers. It 
is safer, therefore, to mix it with other manure ; and generally 
it may be substituted for it at the rate of about 1 cwt. of rape- 
dust for each ton of farmyard manure. 

7. Ilemjp, ;pojppy, and cotton cakes — the refuse of crushed 
hemp, poppy, or cotton seed — may be used for similar purposes, 
and in the same way, as rape-cake. 

8. Cocoa-nut cake, left by the expressed cocoa-nut, is also a 
valuable manure, and has alone been found to produce large 
crops of potatoes. 

These different kinds of cake all contain a large per-centage 
of nitrogen, (4 to 4i per cent,) or, in other words, of protein 
compounds. These ferment very easily, promote growth ra- 
pidly, and give to the manures that contain them peculiar 
fertilising virtues. 

SECTION IV. OF THE USE OF PEAT, PEAT COMPOST, AND TANNER's 

BARK. 

1. Natural jpeat. — In many parts of the world — and in none 
more abundantly, perhaps, than in some parts of our own islands 



PEAT, NATURAL AND FERMENTED. 179 

— vegetable matter continually accumulates in the form of peat. 
This peat ought to supply an inexhaustible store of organic 
matter for the amelioration of the adjacent soils. We know 
that by draining off the sour and unwholesome water, and 
afterwards applying lime and clay, the surface of peat bogs may 
be gradually converted into rich corn-bearing lands. It must, 
therefore, be possible to convert peat itself by a similar process 
into a compost fitted to improve the condition of other soils. 

2. Fermented feat. — The late Lord Meadowbank, who made 
many experiments on this subject, found, that after being par- 
tially dried by exposure to the air, peat might be readily fer- 
mented, and brought into the state of a rich fertilising compost, 
by the same means which are adopted in the ordinary ferment- 
ing of straw. He mixed with it a portion of animal matter, 
which soon communicated its own fermenting quality to the sur- 
rounding peat, and brought it readily into a proper heat. He 
found that one ton of hot fermenting manure, mixed in alternate 
layers with two of half-dried peat, and covered by a layer of 
the same peat, was sufficient to ferment the whole. He observed 
afterwards, also, that the vapors which rise from naturally 
fermenting farmyard manure or animal matters, would alone 
produce the same effect upon peat, placed so as readily to 
receive and absorb them. 

As ammonia is one of the compounds specially given off by 
putrefying animal substances, it is not unlikely that a watering 
with ammioniacal liquor would materially prepare the peat for 
undergoing fermentation. At all events, it seems possible to 
prepare any quantity of valuable peat compost by mixing the 
peat with a little soil, and with a still smaller quantity of fer- 
mented manure than was employed by Lord Meadowbank, pro- 
vided the liquid manure of the farmyard be collected into a 
cistern, and be thrown at intervals, by means of a pump, over 
the prepared heaps. 

After being partially dried, natural peat may be very benefi- 



180 PEAT COMPOST : CILUIRED PEAT. 

cially employed in absorbing the liquid manure of tlie farmyard, 
or in mixing with the contents of the tanks. 

3. Mr. FUming^s peat compost. — Many other ways of working 
up peat have been suggested, such as adding lime, salt, and 
other substances, to aid the fermentation. The most successful 
of these mixtures with which I am acquainted is one which has 
been used with much advantage on the home farm of Mr. Flem- 
ing of Barochan. This compost consists of — 

Sawdust, or dry earthy peat, - - 40 bushels. 

Coal-tar, - - - - - 20 gallons. 

Bone-dust, .... 7 bushels. 

Sulphate of soda, - - ... 1 cwt. 

Sulphate of magnesia, - - - IJ " 

Common salt, - - - - I2 " 

Quick-lime, - - - - 20 bushels. 

These materials are mixed together and put into a heap, and 
allowed to heat and ferment for three weeks, then turned, and 
allowed again to ferment, when the compost is ready for use. 

Compared with farmyard manure and guano, this mixture 
gave on hay and turnips — 

1°. On hay per imperial acre. 

Produce. Cost. 
Nothing, - - 416 stones. 

Guano, 3 cwt. - - *?52 ... $7 50 

Compost, 40 bushels, 761 ... 5 00 

2°. On turnips, (Jones' yellow top.) 

Produce. Cost. 
Farmyard manure, 28 yards, 26 tons. 

Guano, 5 cwt. . . 18 .. $12 50 

Compost, 64 bushels, . 29 . . 7 75 

According to these results, this compost is superior even to 
guano. The experiments, however, require repetition, and the 
results will no doubt vary with the kind of soil and of crop to 
which the compost is apphed. 

4. Charred peat. — By being built up and charred or half 
burned in covered heaps, peat may be obtained in a state in 



USE OF CHARCOAL POWDER. 181 

wliich it is easily reduced to powder. In this powdery state, it 
lias been used alone for turnips, at the rate of 50 bushels an 
acre, and was found to give as good a crop as 50 carts of farm- 
yard dung. Something of this action, however, may have de- 
pended upon the nature of the soil, and upon the kind of peat. 
Charred peat forms, hkewise, an excellent absorbent for the 
liquids of the farmyard and the stable, and for drying up dis- 
solved bones. 

5. Tanners'' hark. — I may here advert also to the use of tan- 
ners' bark, a form of vegetable matter which, like sawdust and 
peat, is difficult to work up, and is therefore often permitted 
largely to go to waste. Like peat it may be dried and burned 
for the ash, which is light, portable, and forms a valuable top- 
dressing. But the economist will prefer to ferment it in a 
compost, in the way above described for peat. An occasional 
watering of the compost with the liquid manure of the farm- 
yard will bring it into a heat, and when the ammoniacal liquor 
of the gas-works can be procured at a cheap rate, it may be 
employed for a similar purpose. The hard thick fragments of 
bark, however, cannot be so soon decomposed as the already 
finely divided peat, and must be expected therefore to demand 
more time. With lime it may, like sawdust or peat, be reduced 
and charred. 

SECTION V. MANURING WITH ARTIFICIALLY DECOMPOSED VEGETABLE 

SUBSTANCES CHARCOAL, SOOT, COAL-TAR, &C. 

When wood and other vegetable substances are heated in 
close vessels they are converted into charcoal. Coal, which is 
of vegetable origin, deposits in our chimneys, when burned, 
large quantities of soot ; and when distilled in gas-retorts it 
yields, besides gas, a quantity of coal-tar and other products. 
All these substances have been tried and recommended as ma- 
nures. 

1°. Charcoal powder possesses the remarkable properties of 



182 EXPERIMENTS WITH SOOT. 

absolving noxious vapors from the air and from the soil, and of 
extracting unpleasant impurities as well as saline substances 
from water, and of decomposing many saline compounds. It 
also sucks into its pores much oxygen and other gases, from the 
air. Owing to these and other properties, it forms a valuable 
mixture with liquid manure, nightsoil, farmyard manure, ammo- 
niacal liquor, or other rich applications to the soil. It is even 
capable itself of yielding slow supplies of nourishment to living 
plants ; and it is said in many cases, even when unmixed, to be 
used with advantage as a top-dressing in practical agriculture.* 
In moist charcoal the seeds of the gardener are found to sprout 
with remarkable quickness and certainty ; but after they have 
sprouted, they do not continue to grow well in charcoal alone. 
Drilled in with the seed, charcoal powder is said greatly to 
promote the growth of wheat. 

2°. Soot, whether from the burning of wood or of coal, con- 
sists chiefly of a finely divided charcoal, possessing the proper- 
ties above mentioned. It contains, however, ammonia, gypsum, 
nitric acid, and certain other substances in considerable quan- 
tity, to which its well-known effects upon vegetation are chiefly 
to be ascribed. In many localities it increases the growth of 
the grass in a remarkable degree, and as a top-dressing to 
wheat and oats, it sometimes produces effects equal to those 
which follow the use of the nitrates of potash or soda.f 

Thus wheat and oats dressed with soot, in comparison with 
undressed, gave the following return of grain — 





Wheat. 


Oats. 


Undressed, 


44 bushels. 


49 bushels. 


Dressed^ 


54 


55 .. 



Increase, .10 6 

* This may no doubt be in part owing to its aiding the production, as all 
porous substances do, of ammonia in its interior, and hence of apocrenate of 
ammonia (p. 23) in the soil, but in part also to its power of decomposing 
other substances. 

f Journal of the Boy al Agricultural Society of England, ii. p. 259. 



COAL DUST AND COAL TAR. 183 

It acts also upon root crops — 56 bushels of soot mixed with 6 
of common salt having produced larger crops of carrots than 24 
tons of farmyard manure, with 24 bushels of bones.* 

I have lately examined several varieties of soot, and find 
that it contains from 18 to 48 per cent of mineral matter, con- 
sistiug of earthy substances from the coal carried up into the 
chimney by the draught, and of gypsum and sulphate of mag- 
nesia derived from the lime of the flue and the sulphur of the 
coal. It contains besides from 1 to 2 per cent of ammonia, 
chiefly in the state of sulphate. These proportions of ammonia, 
calculated in the state of sulphate of ammonia, are equal to 
from 5 J to 12 per cent of the whole weight of the soot. It is 
cot wonderful, therefore, that its ejffects should resemble, and 
even rival, those of the nitrate of soda and of the sulphate of 
ammonia. 

When applied to grass in spring it is said to give a peculiar 
bitterness to the pasture, and even to impart a taste to the 
milk. Hence, in large towns, the cow-feeders of the milk- 
dairies are unwilling to purchase early grass which has been 
manured with soot. 

3°. Coal-dust. — In the county of Durham the dust of com- 
mon coal, such as is sifted out at the mines as too small for 
burning, has been spread upon poor, cold, arable land, and as 
a top-dressing upon old pastures, wdth manifest advantage. 
Something will, no doubt, depend both upon the quality of the 
coal and upon the kind of land to which it is applied. 

4°. Coal-tar applied to the wheat-stubble with a water-cart, 
at the rate of 180 gallons to the imperial acre, and allowed to 
remain two or three months before it is ploughed in, is said 
greatly to benefit the after crop of roots. It has been tried 
on a sandy loam, and on a deep clay. It has also been used 
in the form of compost. 

* Journal of the Royal Agricultural Society of England, iv. p. 270. 



184 



DIFFERENT VEGETABLE MANURES. 



SECTION VI. RELATIVE FERTILISING AND MONEY VALUES OF 

DIFFERENT VEGETABLE MANURES. 



There are two principles on which the relative values of dif- 
ferent vegetable substances, as manures, may be estimated ; — 
first^ by the relative quantity and kind of inorganic matter they 
respectively contain ; and second, by the relative proportions of 
nitrogen present in each. 

1. Yalued according to the quantity oi inorganic matter they 
contain, the worth of the several kinds of straw, hay, &c., 
would be represented by the following numbers : A ton loeight 
of each substance, when made into manure — provided nothing 
is washed out by the rains — will return to the soil the following 
quantities of inorganic matter in pounds :- 



Wheat-straw, . . . . 


•70 to 3.60 


Oat-straw, .... 


100 to 180 


Hay, .... 


100 to 200 


Barley-straw, 


100 to 120 


Pea-straw, . . . " . 


100 to 110 


Bean-straw, 


100 to 130 


Rye-straw, .... 


50 to 100 


Dry potato-tops. 


400 


Dry turnip-tops, 


370 


Rape, and other cakes, 


120 


Malt-dust, .... 


180 


Dried sea-weed. 


560 



Generally, perhaps, these numbers will give the reader a tolero,- 
bly correct idea of the relative permanent eifects of the above 
different kinds of vegetable matter, when laid upon the soil. 
But a reference to the facts stated in pp. 64 to 13, in regard to 
the quality of the inorganic matter contained in plants, will sat- 
isfy him that the effect of these manures on particular crops is 
not to be judged of solely by the absolute quantity of earthy 
and saline matter they contain. What the turnip-top, for 
example, or the bean-stalk, returns to the soil, may not be 
exactly what will best promote the growth of wheat. 



EFFECTS OF THEIR NITROGEN ON THEIR VALUE. 



185 



2. On the other hand, if the fertilising value of vegetable 
substances is to be calculated from the relative quantities of ni- 
trogen they severally contain, we should place them in the fol- 
lowing order ; — the number opposite to each suljstance repre- 
senting that weight of it in pounds which would produce the 
same effect as 100 pounds of farmyard mamlre, consisting of 
the mixed droppings and litter of cattle. (Boussingault.) 



' 






Equivalent 


quantities in 


pounds. 


Farmyard manure, . . . . 100 


"Wheat-straw, 






80 to 170 


Oat-straw, . 






150 


Barley-straw, 






180 


Buckwheat-straw, . 






85 


Pea-straw, . 






45 


Wheat-chaff, 






50 


Green grass, 






80 


Potato-tops, 






•75 


Fresh sea-weed, 






80 


Dried sea-weed, 






20 


Bran of wheat or Indian coi 


'Qj 




26 


Malt-dust, . 






13 


Eape, and other cakes, 






8 


Pir sawdust, 






250 


Oak sawdust, 






180 


Coal-soot, 






20 to 30 



This table again presents the same substances in a somewhat 
different order of value ; showing, for example, not only that 
such substances as rape-dust, malt-dust, and soot, should pro- 
duce a much more remarkable effect upon vegetation than the 
same weight even of farmyard manure, but also that certain 
dry vegetables, such as bran, chaff, and pea-straw, will yield, 
when not unduly fermented, a more enriching manure than the 
straw of barley, oats, or wheat. It agrees also with the known 
effect of green manuring upon the land, since 80 'pounds of 
meadow grass ploughed in should, according to the table, be equal 
in virtue ^o 100 of farmyard manure. 

Some writers ascribe the entire action of these manures to the 



186 GENERAL CONCLUSIONS. 

nitrogen they contain. This, however, is taking a one-sided 
view of their real natural operation. The nitrogen, during their 
decay, is liberated chiefly in the form of ammonia, — a compar- 
atively evauescent substance, producing an immediate effect in 
hastening or carrying farther forward the growth of the plant, 
but not remaining permanently in the soil. The reader, there- 
fore, will form an opinion consistent alike with theory and with 
practice, if he concludes — 

1. That the immediate effect of vegetable manures in hasten- 
ing the growth of plants is dependent, in a great degree, upon 
the quantity of nitrogen they contain and give off during their 
decay in the soil ; but — 

2. That their jpeiinanrnt effect and value is to be estimated 
chiefly by the quantity and quality of the inorganic matter they 
contain — of the ash they leave when burned. 

The effect of the nitrogen may be nearly expended in a sin- 
gle season; that of the earthy and saline matters may not be 
exhausted for several years. 

Kor is the carbon of vegetable substances without its im- 
portant uses to vegetation. From the statements contained in 
the earlier chapters of the present work — especially in reference 
to the production of ammonia and nitric acid in the soil, 
through the agency of decaying carbonaceous matter — it may 
be inferred that, however much influence we may allow to the 
nitrogen and to the earthy matter of plants in aiding the 
growth of future races, the soundest view is that which con- 
siders each of the elements present in decayed or decaying plants to 
he capable either of ministering to, or of p/reparing food for, such 
as are still alive. We may not be able as yet to estimate the 
precise importance of each element to any particular kind of 
crop or soil, or so to adjust the quantities of each in our 
manures, as to promote the growth of that crop upon that soil, 
in the greatest possible degree, yet the principle itself is a 
sound one, and will hereafter guide us to safe and correct 
results. 



CHAPTER XIY. 

Animal manures. — Flesh, fish, shell-fish. — Insects. — Blood. — Animalised 
charcoal. — Skin, horn, hair, wool. — Woollen rags. — Shoddy. — Horn-saw- 
dust, and hoof parings. — Cause of the fertilising influence of these ma- 
nures. — Composition and use of bones and horn-flints. — Preparation of 
dissolved bones. — Comparative experiments with crushed and dissolved 
bones. — Why solution in acid makes bones more active. — Comparative 
action of flesh, blood, horn, woollen rags and bones. — Use of the liquid 
excretions of animals. — Urine of man, the cow, the horse, and the pig. — 
Construction of liquid-manure tanks. — Urate. — Sulphated urine. 

The animal substances employed as manures consist chiefly 
of the flesh, blood, bones, horns, and hair of sea and land ani- 
mals, and of the solid and liquid excrements of land animals 
and birds. 

SECTION I. OF FLESH, FISH, BLOOD, AND SKIN, AND OF THEIR USE 

AS MANURES. 

Animal substances, in general, act more powerfully as ma- 
nures than vegetable substances; it is only the seeds of plants 
which can be at all compared with them in efficacy. 

1. The flesh of animals is rarely used as a manure, except in 
the case of dead horses or cattle which cannot be used for 
food, 

2. Fish are, in this country, chiefly applied in the form of 
the refuse of the herring and pilchard fisheries, though occa- 
sionally such shoals of sprats, herrings, dog-fish, and even 
mackerel, have been caught on our shores, as to make it neces- 
sary to employ them as manure. These recent animal sub- 
stances are found to be, for the most part, too strong when 
applied directly to the land; they are usually, therefore, made 



188 FISH AS A MANURE. 

into a compost, with a large quantity of soil. Five barrels of 
fish, or fish refuse, made into twenty loads of compost, will be 
sufficient for an acre. 

On the coast of Norfolk, large quantities of sprats are used as a 
manure for the turnip crop. They are sold for about 8d. a bushel. 
A ton and a half, mixed with twelve to fifteen cwt. of mould 
taken from the head of the field, makes a compost which is suffi- 
cient for an imperial acre, and is said never to fail. On the 
shores of Aberdeenshire, dog-fish are caught and applied as a 
manure. 

In Rhode Island and the adjoining States, considerable quan- 
tities of manure are made by mixing the fish called menhaden, 
of which large numbers are taken in the bays, with peat or 
swamp mud, in the proportion of one load of fish to ten of peat 
or mud. As many as 150 tons of this fish have been taken at 
a single haul, and sold to the farmers at about 2s. 6d. the thou- 
sand fish, or waggonload.* On the coasts of Connecticut large 
quantities of fish, called white fish, are caught and sold for 
manure, at the rate of about a dollar (4s.) a thousand, weigh- 
ing 15 or 20 cwt. They are either laid on the land and ploughed 
in, or are made into a compost. In the north of China, prawns 
and other kinds of fish are collected and employed for manuring 
purposes. 

The refuse of the fish oils, of the fat of animals that has been 
malted for the extraction of the tallow, of skins that have been 
boiled for the manufacture of glue — as also horns, hair, wool, 
woollen rags, and all similar substances, when made into com- 
posts — exercise, in proportion to their weight, a much greater 
Influence upon vegetation than any of the more abundant forms 
of vegetable matter. 

3. Shell-fish, when they abound on our coasts, have been found 
to be capable of economical application to the land, even for 
raising turnips and potatoes. They are mixed with a little 

* See the Author's Notes on North America, vol. ii. p. 231. 



INSECTS AND BLOOD. 189 

eartli into a ricli compost, and allowed slightly to ferment. If 
the means of crushing them be at hand, their value is by this 
process considerably increased. On the northern shores of the 
Solway, near Annan, the common mussel is found in such quan- 
tities in some places, that, when the tide recedes, a cart-load 
can be raked out of the sand in so short a time as to make it 
a very economical manure. The Rev. Mr. Gillespie of Cum- 
mertrees informs " me, that 700 cart-loads were collected and 
applied to the raising of turnips during the year 1844. They 
are used without other manure, at the rate of about 50 bushels 
to the Scotch acre. On the coasts of Lincolnshire, also, they 
are met with in some places in large quantities, and collected 
for use as a manure. 

4. Even the bodies of insects in many parts of the world form 
important manures. In warm climates, a handful of soil some- 
times seems almost half made up of the wings and skeletons of 
dead insects : in Hungary and Carinthia the peasant occasionally 
collects as many as 30 cart-loads of dead marsh-flies in a single 
year ; and in the richer soils of France and England, where 
worms and other insects abound, the presence of their remains 
in the soil must aid its natural productiveness. 

5. Blood is in this country very seldom, applied to the land 
directly. Like the other parts of animals, however, it makes 
an excellent compost. In Northamptonshire, such a compost is 
made by mixing about 50 gallons of blood with 8 bushels of 
peat-ashes and charcoal powder, and allowing the mixture to 
stand for a year or two. On light soils, this compost raises 
excellent turnips when applied olone, at the rate of 6 quarters 
(48 bushels) per imperial acre — or of 2 quarters with 12 tons 
of farmyard dung. As a top-dressing to young wheat, 20 or 30 
bushels an acre greatly increase the crop. On heavy and wet 
lands, its effects are less perceptible. In that part of England 
the blood is contracted for at the rate of 3d. a gallon. In some 
countries the blood is dried, and in the state of powder is applied 
as a top-dressing to the growing crops. In this state it is sold 



190 WOOLLEN RAGS AND SHODDY. 

in Paris at about 8s. a cwt. — a moderate price, if it be tolera- 
bly dry. Samples prepared in London, and containing still 22 
per cent of water, have also been valued at £S or .£9 a ton. 
But this mode of using blood is not very widely adopted. 

6. Animalised charcoal. — As blood comes from the sugar re- 
fineries, however — in which, with lime-water and animal char- 
coal, it is employed for the refining of sugar — it has obtained 
a very extensive employment, especially in the south of France. 
This animal black, or animalised charcoal, as it is sometimes 
called, contains about 20 per cent of blood, and has risen to 
such a price in France that the sugar refiners actually sell it 
for more than the unmixed blood and animal charcoal originally 
cost them. This has given rise to the manufacture of artificial 
mixtures of charcoal, fecal matters, and blood, which are also 
sold under the name of animalised charcoal. A great disad- 
vantage attending the use of these artificial preparations is, 
that they are liable to be adulterated, or, for cheapness, pre- 
pared in a less efficient manner. 

Y. Skin. — Fragments of skin are sometimes used as a ma- 
nure. The parings of skins from the tan-works are Boiled by 
the glue-makers, and the insoluble refuse is sold as a manure. 
This refuse, in the form of compost, ought to nourish the crops 
very much. When used alone for potatoes, it is said to make 
them waxy on soils where, with other manures, they grow mealy 
and dry. 

SECTION IL OF HAIR, WOOL, WOOLLEN RAGS, SHODDY, HORN-SAW- 
DUST, AND HOOF-PARINGS. 

1. Horn, hair, and loool, depend for their efficacy precisely ou 
the same principles as the blood and flesh of animals. They 
differ chiefly in this, that they are dry, while blood, flesh, and 
fish contain about 80 per cent of their weight of water. 
Hence, one ton of horn-shavings, of hair,* or of dry woollen 

* In China, the hair, which every ten days is shaven from the heads of the 
entii'e population, is collected and sold for manure throughout the empire. 



NITROGEN IN ANIMAL MANURES. 191 

rags, ought to enrich the soil as much as 4 to 5 tons of blood. 
In consequence, however, of their dryness, the horn and wool 
decompose much more slowly than the blood. Hence the effect 
of soft animal matters is more immediate and apparent, while 
that of hard and dry substances is less visible, but continues 
for a much longer period of time. 

2. Woollen rags, when made into a compost and fermented, 
form an excellent manure for potatoes or turnips. In the hop 
countries, they are buried at the roots of the hop plants with 
great advantage. They sell at about £5 a ton. On the sandy 
land in Wiltshire, they are frequently used as a manure for 
turnips. 

3. Shoddy, or mill-waste — the waste of the woollen and 
cloth mills of Yorkshire — is nearly the same thing as hair and 
woollen rags. It sells at about £2 a ton, and is extensively 
used by the farmers of Kent and Northampton. 

4. Horn-saiodiist and hoof-parings. — The small dust, parings, 
turnings, and siftings of horn from the shops of the comb-makers, 
as well as the hoofs of cattle, are now sold to the prussiate of 
potash manufacturers at the rate of about £2 a ton. If they 
were free from admixture, they should be worth to the farmer 
about the same price as woollen rags. They are usually mixed 
with much sand and dust — amounting sometimes to 50 or 60 
per cent of their whole weight. In this state they are not 
worth more than two-fifths of the price of dry hair or woollen 
rags. They may be used instead of bones for the turnip or 
potato crop, but should be made into a fermented compost 
before they are employed as a top-dressing. 

SECTION II. CAUSE OF THE FERTILISING INFLUENCE OF THE ABOVE 

ANIMAL MANURES. 

The fertilising influence of the parts of animal bodies, described 
in the preceding sections, depends mainly upon their consisting, 
for the greater part, of substances very rich in nitrogen. Thus — 



192 HORN AND BONES. 

Percentage of 
nitrogen. 
Dry blood, flesh, and fish contain about . . 15| 

Dry skin, hair, wool, horns, and hoofs, . . 16 to 17^ 

But these two classes of substances differ much in the quan- 
tity of water they contain — 

Percentage 
of water. 
Blood, fish, and flesh, contain . . . 78 to 82 

Hair, wool, and. horn, . . . . 10 to 15 

Skin and hoofs vary much in dryness, and therefore the aver- 
age proportion of water in them cannot be estimated. 

The special differences of the above substances as manures 
depend mainly upon those differences in the proportion of water. 
Blood, fish, and flesh decompose rapidly, act quickly," and pro- 
mote growth speedily. Wool, hair, and horn take a long time 
to rot, are not so well adapted, therefore, for promoting speedy 
growth, but by their gradual decay are better fitted to afford 
prolonged nourishment to a crop which continues long in the 
ground, or permanently to enrich a soil which has been exhausted 
by too severe cropping. 

The mineral matter contained in these substances is small in 
quantity, and therefore of comparatively little influence upon 
their manuring value. Dry blood and flesh leave about 4 per 
cent of ash, while wool, hair, and horn leave only 1 or 2 per 
cent. The ash of flesh and fish consists almost entirely of phos- 
phates, and that of blood in great part of common salt. This 
may influence their respective action upon plants — as the fact 
that hair contains 5 per cent of sulphur may also modify the 
action of this substance as a manure. (See p. 000.) 

SECTION IV. COMPOSITION OF BONES AND THE PITH OF HORNS, AND 

THEIR VALUE AS MANURES. 

1. Bones, while they resemble hair and horn in being dry, 



HORN, FLINT OR PITH. 193 

diflfer from them in containiug a large quantity of earthy matter, 
and hence they introduce a new agent to aid their effect upon 
the soil. Thus, the bones of the cow consist in 100 lb. of — 



Phosphate of lime, , 


55J 


Phosphate of magnesia, 


2 


Soda and common salt, 


2i 


Carbonate of lime, . . . . 


31 


Fluoride of calcium. 


3 


Gelatine (the substance of horn,) . 


33i 



100. 

While 100 lb. of dry bone-dust, therefore, add to the soil as 
much organic animal matter as 33 lb. of horn, or as 300 to 400 
lb. of blood or flesh, they add at the same time two-thirds of 
their weight of inorganic matter, consisting of lime, magnesia, 
soda, common salt, and phosphoric acid (in the phosphates) — 
all of which, as we have seen, must be present in a fertile soil, 
since the plants require a certain supply of them all at every 
period of their growth. These substances, like the inorganic 
matter of plants, may remain in the soil, and may exert a be- 
neficial action upon vegetation after all the organic or gelati- 
nous matter has decayed and disappeared. 

2. Horn Jlints, or piths, resemble bone very much in compo- 
sition. They contain a little more animal matter, and from 
their softness and porosity are more difiicult to crush in the 
mill. For the same reason, however, they decay more rapidly 
in the soil, and act more immediately than bones. They boil 
down, however, more readily than bones, and are therefore 
largely used for making the size used in stiffening calicoes. 
For this purpose they are sold by the comb-makers at about 
£4 a ton. 

When they are not in demand for this purpose they may be 
very usefully employed as a manure. 

A sample of the pith, as it is sold in tlie market, gave to 
Professor Norton in my laboratory — 
9 



194 PREPARATION OF DISSOLVED BONES. 

Water, (lost at 212",) . . . 10.31 • 

Phosphates of lime and magnesia, . 46.14 

Carbonate of lime, . . . . "/.Tl 

Gelatine, (organic matter,) . . . 35.84 

100. 

SECTION V. PREPARATION OF DISSOLVED BONES. COMPARATIVE EX- 
PERIMENTS WITH CRUSHED AND DISSOLVED BONES, WHY THIS 
SOLUTION MAKES BONES MORE ACTIVE. 

For the purpose of bringing bones into a state in which the 
substances they contain can be more readily taken up by the 
roots of plants, and at the same time more uniformly distri- 
buted through the soil, the method has been adopted of dis- 
solving them in sulphuric acid. For this purpose, the bone-dust 
is mixed with one-half its weight, and sometimes with its own 
weight of sulphuric acid (the oil of vitriol of the shops,) 
previously diluted with from one to three times its bulk of 
water. Considerable effervescence takes place at first, from 
the action of the acid upon the carbonate of lime in the bones; 
but, after two or three days, with occasional stirring, the bones 
are entirely dissolved or reduced. The solution or paste may 
now be dried up with charcoal powder, with dried or charred 
peat, with sawdust, or with fine vegetable soil, and applied 
with the hand or with the drill to the turnip crop ; or it may 
be diluted with 50 times its bulk of water, and let off into the 
drills with a water-cart. Applied either way, the effect is 
much more striking than when the same weight of bone-dust is 
applied in the ordinary form. Thus — 

a. At Gordon Castle (Mr. Bell) the following results were 
obtained : — 

Manure per Imperial Acre. Cost. -p. , , Hvbrid ' 

3 cwt. guano, 1 17 ( 9.2C) 11-2 .. 

16 bushels bones, 1 16 ( 9.00) 11 



EXPERIMENTS WITH DISSOLVED BONES. 195 

Manure per Imperial Acre. Cost. ■^^°^"''®x?^?"i^^' 

Dale s Hybrid. 
2 bushels bones, ) 

83 lb. sulphuric acid, I £0 11 6 ($2.88) 12-2 .. 

400 gallons water, \ 

8 bushels bones, j 

83 1b. sulphuric acid — I 1 5 ( 6.25) 11 

sown with the hand. ) 

The largest produce was here obtained, when the dissolved 
bones were applied with a water-cart, and at a cost of eleven 
shillings per acre. 

b. Again, on the farm of Sherriffstoun in Morayshire, (Mr. 
M' William,) the following comparative results were obtained in 
1843 :— 



1. Swedish Turnips. 




Manures. 


Cost per Produce in Bulbs per 




Acre. 


Imperial Acre. 


•75 lb. (1-6 bushels) bones, 


' £0 9 3 ($2.31) 




46 lb. acid, 


IT -5 tons. 


400 gallons water, 




The same with 200 gallons 
water. 


9 3 ( 2.31) 


18-5 .. 


440 lb. (9-5 bushels) bones, 
28 lb. of acid, 


I 1 4 9 ( 6.19) 


IT 


2. Common Turnips. 




170 lb. (3-2 bushels) bones, " 


) 




92 lb. acid, 


[■ £0 1*7 6 ($4.38) 


16 tons. 


400 gallons water, ' 


\ 




16 bushels bones, . 


) 




46 lb. acid, 


- 2 2 ( 5.50) 


13-5 . . 


10 gallons water, j 


1 





In all these cases the smaller quantity of bones, when dis- 
solved in acid and applied in a liquid state, gave a heavier 
return of bulbs than the larger quantity when drilled in dry. 
Even the watering of the large quantity of bones with a portion 
of acid, did not make their effect on the crop equal to that of 
the small quantity of dissolved bones. 



196 



INFLUENCE OF THE SULPHURIC ACID. 



Mr. Hannam obtained, by the use of crushed and dissolved 
bones upon turnips, the following results : — 



Tons. 


cwts. 




10 


3 per 


imperial 


9 


12 




11 


15 




12 


11 




14 


6 




14 


11 




13 


15 




15 


2 




16 


1 





Bones. 
16 bushels, crushed, gave 
2 . . dissolved, 
2 
4 
4 
4 



We can explain this superior action of dissolved bones by the 
fact, that the dissolving separates their particles completely from 
each other, diffuses them more completely through the soil, and 
presents them to a larger surface of the turnip roots, and in a 
state in which they can be more readily absorbed. The sul- 
phuric acid also may have some effect, since we know that sul- 
phur, in some form, is necessary to the growth of all our crops. 
I have indeed been informed of a case at Balcarras, in Fifeshire, 
where diluted sulphuric acid applied alone to the drills produced 
an excellent crop of turnips ; and of another in Dumfriesshire, 
where steeping the seed-corn in diluted sulphuric acid added 
many bushels to the crop of barley. 

Though the immediate effect of a small quantity of bones on 
the first crop is made so much greater by this mode of applying 
them, it is not to be expected that the effect upon the after 
crops should be as beneficial as when a larger quantity of bones 
is applied in the ordinary method. 

SECTION VI. COMPARATIVE ACTION OF FLESH, BLOOD, HORN, WOOLLEN 

RAGS, AND BONES. 



From what has been stated in the preceding sections the 
reader will gather these general conclusions — 

] . That animal substances which, like flesh and blood, con- 



GENERAL CONCLUSIONS. l^t 

tain much water, decay rapidly, and are fitted to operate imme- 
diately and powerfully upon vegetation, but are only temporary 
or evanescent in their action. (P. 192.) 

2. That when dry, as in horn, hair, and wool, they decom- 
pose — and consequently act — more slowly, and continue to ma- 
nifest an influence, it may be, for several seasons. 

3. That bones and horn flints act like horn, in so far as their 
animal matter is concerned, and, like it, for a longer or shorter 
time, according as they have been more or Tess finely crushed; 
but that they ameliorate the soil by their earthy matter for a 
still longer period — permanently improving the condition, and 
adding to the natural capabilities of the land. 

4. That the action of bones may be rendered more imme- 
diate and striking by bringing them into a minute state of di- 
vision, — as by dissolving them in diluted sulphuric acid, or by 
fermenting them in a mixture of moist sand or soil — but that, 
like flesh and blood, their effect, by that means, is likely to be 
rendered less permanent. 



SECTION VII. OF THE URINE OF ANIMALS, AND THE MEANS OP 

PRESERVING AND APPLYING IT. URATE. SULPHATED URINE, &C. 

Practical men have long been of opinion that the digestion 
of food, either animal or vegetable, — its passage through the 
bodies of animals — enriches its fertilising power, weight for 
weight, when added to the land. Hence in causing animals to 
eat up as much of the vegetable productions of the farm as 
possible — of the straw and turnip-tops, for example, as well as 
of the grain and bulbs — it is supposed that not only is so much 
food saved, but that the value of the remainder in fertilising 
the land is greatly increased. In a subsequent section we shall 
see how far theory serves to throw light upon these opinions. 

The digested animal substances usually employed as manures 
are — the urine of man, of the cow, and of the sheep; the solid 
excrements of man (nightsoil,) of the horse, the cow, the 



198 THE URINE OF MAN. 

sheep, and the pig, and the droppings of pigeons and other 
birds. The liquid manures act chiefly through the saline sub- 
stances which they hold in solution, while the solid manures 
contain also insoluble matters which decay slowly in the soil, 
and there become useful only after a time. The former, there- 
fore, will influence vegetation more powerfully at first ; the 
action of the latter will be less evident, but will continue to be 
sensible for a much longer period of time. 

1. Tht urim of man. — Human urine consists, in 1000 parts 
of— 

Water, 932 

Urea, and other organic matters containing nitrogen, 49 

Phosphates of ammonia, soda, lime, and magnesia, . 6 

Sulphates of soda and ammonia, .... 7 

Sal-ammoniac, and common salt, .... 6 

1000 
1000 lb. of urine, therefore, contain 68 lb. of dry fertilising 
matter of the richest quality, worth, at the present rate of sell- 
ing artificial manures in this country, at least 10s. a cwt. As 
each full-grown man voids about 1000 lb. of urine in a year, the 
national waste incurred in this form amounts, at the above va- 
luation, to 6s. a head. And if 5 tons of farmyard manure per 
acre, added year by year, will keep a farm in good heart, 4 
cwt. of the solid matter of urine would probably have an equal 
effect ; or the urine alone discharged into the rivers by a popu- 
lation of 10,000 inhabitants would supply manure to a farm of 
1500 acres, and would yield a return of 4500 quarters of corn, 
or an equivalent produce of other crops. Mr, Smith of Deans- 
ton considered the urine of two men to be a suSicient manuring 
for an acre of land, and that when mixed with ashes, it would 
produce a fair crop of turnips,* 

An important chemical distinction exists between the urine 
of man and that of the cow, the horse, and the sheep. It con- 
tains, as is shown in the previous page, about 6 per cent of 

* Report of Committee on Metropolitan Sewerage. 



URINE OF THE COW. 199 

phosphates, while these compounds are entirely absent from the 
urine of the other animals. The presence of the phosphoric 
acid contained in these phosphates, adds very much to the ma- 
nuring value of human urine. 

If milk or lime be mixed with fermenting human urine, this 
phosphoric acid is precipitated with a portion of the animal 
matter. Dr. Stenhouse found a precipitate of this kind, when 
dried at 212°. F.-, to contain 40 per cent of phosphoric acid 
and of organic matter, including about 1 per cent of ammonia. 
By the use of this method, an important part of the fertilising 
ingredients of human urine may be separated in a solid state. 
It has recently been adopted with some success for the purpose 
of separating the fertilising matters contained in sewage 
water. 

2. Pig^s urine. — The urine of the pig resembles that of man, 
in containing a considerable proportion of phosphoric acid. In 
this respect it is more valuable as a manure than those of the 
horse, the cow, and the sheep. 

3. The urine of the coia is said to contain less water than 
that of man, though of course much must depend upon the 
kind of food with which it it is fed. Considering, then, the 
large quantity of liquid manure that is yielded by the cow 
(1200 or 1500 gallons a-year,) we may safely estimate the 
solid matter given off by a healthy animal in the form of urine 
in twelve months, at about 1000 lb. in weight — worth, if it 
icere in the dry state, from £i to £5 sterling. In the liquid 
state, the urine of one cow, collected and preserved as it is in 
Flanders, is valued in that country at about £2 a-year. Any 
practical farmer may calculate for himself, therefore, how much 
real wealth, taking it even at the Flemish value, is lost in his 
own farmyard — how much of the natural means of reproduc- 
tive industry passes into his drains, or evaporates into the 
air. 

This liquid manure is very valuable, when collected in tanks, 
for watering the manure and compost heaps, and thus hasten- 



200 CONSTRUCTION OF LIQUID-MANURE TANKS.' 

ing their decomposition. It may also be sprinkled directly 
upon the fields of grass or of clover, and upon the young corn, 
— or the young green crop (turnips, &c.) may be watered with 
it, with the best effects. It must, however, be permitted to 
stand till fermentation commences, and must afterwards be 
diluted with a considerable quantity of water, before it will be 
in the best condition for laying upon the land. This dilution, 
indeed, where the receiving tanks are large enough, should be 
made at an earlier period, for it has been found that, when un- 
mixed with water, cows' urine, which is six weeks old, contains 
only one-sixth part of the ammonia retained by the same urine 
when.it has been previously diluted with an equal bulk of 
water. Sulphuric acid may also be added to fix the ammonia.* 

4. Of the construction of liquid-manure tanks. — There are four 
practical points which are worthy of attention in the construc- 
tion of tanks for liquid manure. 

a. They ought to be well puddled with clay behind the stone 
or brick work, to prevent any loss or escape of the liquid. 

h. They ought to be covered over, and the closer the better. 
In Germany they are usually vaulted. From close tanks the 
sun, rain, and air, are in a great measure excluded, and the fer- 
mentation is slower, and the loss of ammonia in consequence 
considerably less. 

c. They should be divided by a wall, into at least two com- 
partments, capable of holding each a two or three months' sup- 
ply. When the first of these is full, the stream is turned into 
the second, and by the time it is also full, the contents of the 
first are ripe, or in a fit state for putting upon the land. The 

* To saturate and fix the whole of the ammonia capaUe of being formed 
iu the urine of a single cow of average size, would require about V 00 lb. of 
the common strong sulphuric acid of the shops, or nearly 60 lb. a month, 
costing 9s. One-third or one-fourth of this quantity, however, added to tho 
liquid-manure tank, would be sufficient to prevent any very sensible loss. 
Mr. Kinninmonth found 750 gallons of cows' urine so treated, with about 
15 lb. of acid, equal in increasing the produce of hay to 2^ cwt. of guano, 
or 1 cwt. of nitrate of soda. 



, URATE AND SULPIIATED URINE. 201 

liquid ought always to be in a state of fermentation before it is 
applied either to grass or to any other crop. This double tank 
also enables the farmer to collect and preserve his liquid during 
the three mouths of winter, when it cannot be applied, and to 
have a large supply in a fit state for putting on when the young 
grass or corn begins to shoot. 

The liquid as it comes from the cattle ought to be mixed in 
the tank with at least its own bulk of water. By this means a 
considerable loss of ammonia is prevented which would other- 
wise escape from the urine during fermentation ; and it is pre- 
vented from burning the grass, which in very dry seasons it is 
apt to do when put on without dilution. This necessarily 
involves larger cisterns, and more labor in carrying out the 
liquid ; but experience seems to say that the additional profit 
exceeds considerably the additional expense. 

5. Urate. — Among other methods of obtaining the virtues of 
animal urine in a concentrated form, burnt gypsum is mixed 
with it in the state of powder in the proportion of 10 lb. to 
every t gallons, allowing the mixture^ occasionally stirred, to 
stand some time, pouring off the liquid, and drying the gypsum. 
This is sold by manure manufacturers under the name of urate. 
It never can possess, however, the virtues of the urine, since it 
does not contain the soluble saline substances, which the gypsum 
does not carry down with it. Except the gypsum, indeed, 100 
lb. of urate contain no greater weight of saline and organic 
matter than ten gallons of urine. If it be true, then, as the 
manufacturers state, that 3 or 4 cwt. of urate are sufiicient 
manure for an acre, the practical farmer will, I hope, draw the 
conclusion, — not that it is well worth while to venture his money 
in buying this urate, and trying it upon his land, but that a far 
more promising adventure will be to go to some expense in sav- 
ing his own liquid manure, and after mixing it, if he think 
proper, with the burned gypsum, to lay it abundantly upon all 
his fields. 

6. Sulphated urine. — A better method than that of using 

9* 



202 AJIMONIACO-MAGNESIAN PHOSPHATE. , 

gypsum has been lately adopted by several manure manufac- 
turers. They -mix as much sulphuric acid with the urine as is 
sufficient to combine with and fix the whole of the ammonia 
which may be produced during the decomposition of the urine. 
The mixture is then evaporated to dryness, and is sold and 
applied to the land in the state of a dry powder. 

This sulphated urine, containing as it does all the saline sub- 
stance of the liquid urine, with the addition of sulphuric acid, 
ought to prove a most valuable manure. If prepared from 
human urine, it will promote the growth of nearly all crops ; 
but, from the sulphuric acid it contains, it may exercise a special 
influence on beans, peas, and clovers. As a top-dressing it may 
be applied alone ; but when used for root-crops, it ought to be 
mixed with and to take the place of not more than one-half of 
the farmyard manure usually applied. Used in this way, at a 
cost of £2 an acre, Mr. Finnie of Swanston obtained, in 1843, 
four tons of turnips per imperial acre more than from an equal 
cost of guano. 

As a top-dressing for wheat, and probably also for other corn 
crops, this sulphated urine may be advantageously mixed with 
an equal weight of sulphate of soda or of common salt, with at 
least as much wood ashes, if they can be had, and with half its 
weight of dissolved bones. The soda salts are especially desir- 
able where the land lies remote from the sea. 

1. Ammonia co-ma gnesian pkosp/iaie.- — Boussingault fixes the 
ammonia and phosphoric acid of human urine by adding to it, 
after it has acquired an ammoniacal odor, a solution of sul- 
phate or muriate of magnesia, when the double phosphate of 
magnesia and ammonia falls to the bottom of the liquid. 
About T lb. of this salt are obtained from 100 lb. of urine ; 
and it has been ascertained to possess powerful fertilising pro- 
perties.* 

* In reference to liquid manures, I strongly recommend to my readers, 
the "Minutes of Information collected on the Practical Application of 
Sewer "Water, and Town Manures, to Agricultural Purposes," published by- 
the General Board of Health. 



CPIAPTER XY. 

Animal manures continued. — Solid excretions or droppings of animals. — 
Nightsoil. — Poudr-ette. — Tafl'o. — Cow, horse, and pigs' dung. — Droppings 
^ of birds, — Pigeons' dung. — Guano. — African and -American varieties. — 
Their composition, and fertilising values. — Their durability. — Adultera- 
tion ofj how to test or select a good sample, quantity imported, and va- 
lue to the nation. 

The solid excretions of animals are not less valuable as ma- 
nures than their urines, and in almost every country are much 
more generally employed. 

SECTION I. OF NIGHTSOIL, POUDRETTE, AND TAFFO ; AND OF COW, 

HORSE, AND PIGs' DUNG. 

1. Nightsoil is probably the most valuable of all the solid 
animal manures. It varies in richness with the food of the in- 
habitants of each district,* — chiefly with the quantity of ani- 
mal food they consume, — but when dry, few other solid manures, 
weight for weight, can be compared with it in general efficacy. 
It contains much soluble and saline matter, and as it is made 
up from the constituents of the food we eat, of course it con- 
tains most of those elementary substances which are necessary 
to the growth of the plants on which we principally live. 

2. Poudrette. — Attempts have been made to dry nightsoil so 

* This is said to be so well known in some of the towns in the centre of 
Europe, where a mixed population of Protestants and Roman Catholics live 
together, that the neighboring farmers give a larger price for the house- 
dung of the Protestant families. In Persia, the nightsoil of the Russian 
families is, for a similar reason, preferred to that of the less flesh-eating 
Mahometans. 



^04 cow, HORSE AND PIGs' DUNG. 

as to render it more portable, — to destroy its unpleasant smell, 
so as to reconcile practical men to a more general use of it, — 
and, by certain cliemical additions, to prevent the waste of am- 
monia and other volatile substances, which are apt to escape 
and be lost when this and other powerful animal manures begin 
to putrefy. In Paris, Berlin, and other large cities, the night- 
soil, dried first in the air with or without a mixture of gypsum 
or lime, then upon drying-plates, and finally in stoves, is sold 
under the name of poudrette, and is extensively exported in (^ 
casks to various parts of the country. It is said to be equal 
in efiicacy to 30 times its bulk of horse or street manure, and 
is applied at the rate of from 15 to 35 bushels an acre. 

In London, also, nightsoil is dried with various admixtures; 
and in some of our other large towns an animalised charcoal is 
prepared by mixing and drying nightsoil with gypsum and or- 
dinary wood charcoal, in fine powder. Charred peat would 
answer well for such a purpose. 

Few simple and easily attainable substances would make a 
better compost with nightsoil, and more thoroughly preserve 
its virtues, than half-dried peat, saw-dust, or rich vegetable 
soil, mixed with more or less marl or gypsum. It is impossible 
to estimate the proportion of waste which this valuable manure 
undergoes b^ being allow^ed to ferment, without mixture, in the 
open air, 

3. Taffo. — In China nightsoil is kneaded into cakes with 
clay, which are dried in the air, and, under the name of taffo, 
form an important article of export from all the large cities of 
the empire. In Persia it is dried in the sun and powdered. 
Mixed with twice its bulk of dry soil, it is then used for raising 
the finest melons. 

4. Cow, horse, and pigs' dung. So much of the saline and 
soluble organic matters in the excretions of the cow pass off in 
the liquid form, that its dung is correctly called cold, since it 
does not readily heat and run into fermentation. Mixed with 
other manures, however, or well diffused througn the soil, it 



DROPPIXGS OF BIRDS. 205 

aids materially in promoting vegetation. The horse being fed 
generally on less liquid food, and discharging less urine, yields 
a hotter and richer dung, which is admirably fitted for bringing 
substances into a state of fermentation, but answers best for 
the land when mixed with other varieties of manure. The 
dung of the pig is soft and cold like that of the cow, contain- 
ing, like it, at least t5 per cent of water. As this animal lives 
on moro^ varied food than any other which is reared for the use 
of man, the manure obtained from it is also very variable in 
quality. Applied alone, as a manure to roots, it is said to give 
them an unpleasant taste, and to injure the flavor even of the 
tobacco plant. It answers well for hemp and for hops ; but 
when mixed with other manures, it may be applied to any crop. 
In some districts pigs' dung is considered one of the richest 
and most valuable that can be applied to the land. But the 
most generally useful manure is obtained by mixing all these 
varieties together, as is usually done in the manure -heaps of 
our larger farmers. 

SECTION II. DROPPINGS OF BIRDS. PIGEONS' DUNG AND GUANO. 

AFRICAN AND AMERICAN VARIETIES THEIR COMPOSITION AND FER- 
TILISING EFFECTS. 

1. Pigeons'' dung. — The dung of nearly all birds is distin- 
guished by eminent fertilising properties. Some varieties are 
stronger than others, or more immediate in their action, and 
all are improved for the use of the farmer by being some time 
kept, either alone or in compost. In Flanders the manure of 
one hundred pigeons is considered to be worth 20s. a-year for 
agricultural purposes. In Catalonia, Arragon, and some other 
parts of Spain, pigeons' dung is sold as high as 4d. a pound, 
for applying, when mixed with water, to flower-roots, melons, 
tomatos, and other plants.* 

* The estimation in which it was held in ancient Palestine may be in- 
ferred from the statement, that, during a siege of Samaria, the fourth part 



206 GUANO AND FARMYARD DUNG. 

The dung of birds possesses tlie united virtues of both the 
liquid and solid excretions of other animals. It contains every 
part of the food of the bird, with the exception of what is abso- 
lutely necessary for the support and for the right discharge of the 
functions of its own body. It is thus fitted to return to the 
plant a greater number of those substances on which plants live, 
than either the solid or the fluid excrements of other animals ; 
in other words, to be more propitious to vegetable growth. 

2. Guano is the name given by the natives of Peru to the 
dung of sea-fowl, which in former periods used to be deposited 
in vast quantities on the rocky shores and isles of the Peruvian 
coast. The numerous shipping of modern times has disturbed 
and driven away many of the sea-fowl, so that much less of 
their recent droppings is now preserved or collected. Ancient 
heaps of it, however, mixed with feathers and fragments of 
bone, still exist in many places, more or less covered up with 
drifted sand, and also more or less decomposed. These are now 
largely excavated, especially on the Chincha islands, for expor- 
tation, not only to different parts of the coast of Peru, — as 
seems to have been the case from the most remote periods, — but 
also to Europe, and especially to England. It is at present sold 
in this country at a price which varies from £8 to ^11 a ton. 

Guano was also imported, for a few years, (1843 to 1841,) 
in large quantities from the island of Ichaboe, and from other 
places on the west coast of Africa. The quality of the African 
was not equal, however, to that of the guano brought from 
Peru. It contained more water, and was in a more advanced 
stage of decomposition. The known sources of supply from this 
quarter are now nearly exhausted ; and with the exception per- 
haps of a little from Saldanha Bay, there is none of it now in 

of a cab of doves' dung was sold for 5 pieces of silver. — 2' Kings vi. 25. 
I may state, however, that what is here translated doves' dung, was con- 
sidered by Linneeus to mean the bulbous root of the Ornithogallum umhel- 
latum, still eaten in Palestine, and forming part of the food of some of the 
tribes of Hottentots at the Cape of Good Hope. 



FERTILISING EFFECT OF GUANO. 



20t 



the market. Its price varied with the quality, from £3 to £S 
a ton. 

Guano is capable of entirely replacing farmyard dung, — that 
is to say, turnips and potatoes may be manured successfully with 
guano alone. It may be used either as a top-dressing to the 
young corn and grass ; or it may be put in with the turnip-seed, 
or with the potato cuttings, being previously mixed with a quan- 
tity of fine dry soil, charcoal powder or gypsum. It may also 
be mixed with water, and used as a liquid manure. It is 
applied in various proportions, from one to three, four, or live 
hundred weights per acre. Three cwt. of guano, without other 
manure, gave Mr. Fleming of Barochan 18| tons of potatoes 
per acre ; and 5 cwt., with 20 bushels of wood ashes, gave him 
32 tons of yellow turnips. 

The application of guano to the sugar cane has largely 
increased the produce of sugar, both in the British West India 
Islands and in the Mauritius. 

When applied in too large a quantity, the effect both upou 
the turnip and upon the after corn-crop is of a very hurtful 
kind. This is very strikingly shown ])y the following results 
of an experiment made in Ross-shire (in 1843 and 1844) with 
4, 8, and 1 6 cwt. respectively to the Scotch acre : — 



Quantity of 
Guano. 


Effect on the Turnip Crop 


On the after crop of 
Wheat. 


4 cwt. 
8 .. 

'•■1 


Good turnips, 18 tons. 
Very indifferent, 14 tons. 
Grew up wonderfully, 
looked beautiful, but 
there was little bulb. 
Produce 10 tons. 


Good Wheat. 
Inferior. 

Stubble black, grain 
-/ dark, and not larger 
than small rice. 



3. The fertilising effects of guano depend mainly upou the 
quantity of ammonia which already exists in it, or which may 
be formed in it by its further decomposition, and upon the pro- 



208 



COMPOSITION OF GUANOS. 



portion of phosphates which are present in it. Of these the 
former is the more valuable ingredient of the two — that is to 
say, it would cost the farmer most money to buy it in ^a sepa- 
rate state, at its present price. The phosphates, in like man- 
ner, would cost more to buy in the shape of bones or of sugar- 
refiners' refuse, (animal charcoal,) than any of the other 
ingredients which the guano contains — the ammoniacal matter 
excepted. 

4. Composition. — The following table exhibits the composi- 
tion of four samples of guano, two from the South American 
and two from the African coast. These analyses do not enter 
much into details, but they are sufficient for ordinary purposes 
— as guides, that is, to the practical man. 



Water, - 

Organic matter con- 
taining ammonia. 

Common salt and [ 
sulphate of soda, [ 

Carbonate of lime, 

Phosphates of lime ) 
and magnesia, ) 

Silicious matter or ) 
sand, j" 


South Amkrica.n. 


African. 


Peruvian. 


Bolivian. 


Ichaboe. 


Saldanha 
Bay. 


13.09 
53.17 

4.63 

4.18 

23.54 

1.39 


6.91 
55.52 

6.31 

3.87 
25.68 

1.71 


16.71 
46.61 

12.92 

0.27 

22.4t0 

0.52 


18.35 
22.14 

5.78 

1.49 

50.22 

2.02 


100. 


100. 


99.43 


100. 



These analyses are not to be considered as doing more than 
generally rejprescnting the difference between the African and 
American guanos. The several cargoes, both of African and 
of American, which used to arrive in this country, differed much 
among themselves. As I have already stated, the importation 
of African guano has now almost entirely ceased. 



PERMANENCE OF THEIR ACTION. 209 

It is one of the valuable qualities of guano, that it contains 
a mixture of so many of these substances on which plants live. 
The only ingredient in which it is manifestly defective is potash 
— of which it usually contains less than 1 per cent ; and hence 
an admixture of wood ashes, and especially of leached or washed 
wood ashes, would be likely to improve its action upon the 
crops, in such soils as do not naturally abound in potash. 

5. Lolos Islands guano, which is at this moment attracting 
so much of the attention of politicians, is said to be the pro- 
duce of the seal or sea-wolf, and to be from 25 to 33 per cent 
less valuable than the guano of the Chincha islands. 

6. British guano. — The successful employment of foreign 
guano has caused the droppings of pigeons, sea-fowls, and bats, 
to be sought for in the caves along our east and west coasts, and 
in our western islands. I have examined several samples from 
both coasts ; but though they may prove valuable manures in 
the immediate neighborhood where they are found, they are not 
rich enough to pay the cost of collection and transport to any 
considerable distance. 

t. Is guano permanent in its action ? — This is a question which 
the practical man naturally asks when he is about to employ it 
to a large extent. Experience seems to show that its beneficial 
action extends to at least two crops, when it is applied in proper 
quantity. Theory also indicates, that though the action of the 
ammoniacal salts may be more or less exhausted in a single sea- 
son, yet that the effect of the phosphates and other saline sub- 
stances it contains — which is very important — will continue 
beyond one year. But the kind and quality of the guano will 
materially affect the length of its action. 

In general, however, it may be said, that as guano resembles 
bones very much in its composition, and as bones are known to 
benefit the crops in an entire rotation, so ought guano also. 
The chief difference between bones and guano is this — that the 
guano contains ammonia ready formed, or forming, so to speak 
— while the bones contain gelatine, which forms ammonia only 



210 ADULTERATION OF GUANO. 

after it has fermented. The ammoniacal part of the one, there- 
fore, will act early, of the other after a longer period — while 
the permanent effects of the remaining ingredients of both will 
be very much alike if they are laid on in nearly the same 
proportions. 

SECTION III. ADULTERATIONS OF GUANO HOW TO SELECT A SAM- 
PLE OF GOOD QUALITY NATIONAL VALUE OF THIS MANURE. 

1. Adulterations of guano. — In consequence of the high price 
of guano, the great demand for it, and the ease with which the 
unwary farmer may be imposed upon, guano is adulterated with 
various substances, and to a great extent. Impositions even 
have been practised by selling as genuine guano artificial mix- 
tures, made to look so like guano that the practical man in 
remote districts is unable to detect it. A sample of such pre- 
tended guano, which had been sold in the neighborhood of Wig- 
town, and had been found to produce no effect upon the crops, 
when examined in my laboratory, was found to contain, in the 
state in which it was sold, more than half its weight of gypsum — 
the rest being peat or coal ashes, with a little common salt, sul- 
phate of ammonia, and either dried urine or the refuse of the 
glue manufactories, to give it a smell. I could not satisfy 
myself that it contained a particle of real guano. Burnt earth 
and brick-dust are now prepared of various shades, and in fine 
powder, in special manufactories, for the purpose of mixing with 
guano and with artificial manures. These facts show how 
important it is that the farmer should possess some means of 
readily, and at a cheap rate, testing the costly manures he 
employs.* 

* "Four vessels recently sailed hence for guano stations ballasted with 
gypsum, or plaster of Paris. This substance is intended for admixture with 
guano ; and will enable the parties to deliver from the vessel a nice-looking 
and light-colored article. Parties purchasing guano are very desirous of 
havhig it delivered from the vessel, as they believe they obtain it pure. The 



HOW TO SELECT A GOOD GUANO. 211 

2, In selecting a good guano, the following simple observations 
will aid the practical man. 

a. The drier the better — there is less water to pay for and to 
transport. 

h. The lighter the color, the better also. It is the less com- 
pletely decomposed. 

c. If it has not a strong ammoniacal smell, it ought to give 
off such a smell when a spoonful of it is mixed with a spoonful 
of slaked lime in a wine glass. 

d. When put into a tumbler with water, stirred well about, 
and the water and fine matter poured off, it ought to leave little 
sand or stones. 

e. When heated to redness in the air till all the animal mat- 
ter is burned away, the ash should nearly all dissolve in dilute 
muriatic acid. The insoluble matter is useless sand or earthy 
adulterations. 

/. In looking at the numbers in a published analysis of a 
Peruvian guano, those representing the water should be small ; 
the organic matter containing ammonia should approach to 50 
or 60 per cent ; the phosphates should not much exceed 20 per 
cent ; and the common salt and sulphate of soda ought not to 
form much more than 5 or 6 per cent of the weight of the guano. 
in Saldanha Bay guano the proportion of phosphates was much 
greater, and of organic matter less. 

3. The national value of guano, and the consequent import- 
ance of preventing adulteration as far as possible, may be judged 
of from three important facts. 

a. From the amount of the importation of it into this coun* 
try, which, during the last ten years, has been as follows : — 

favorite material for the adulteration of guano, at the present moment, is 
umber, which is brought from Angiesea in large quantities. The rate of 
admixture, we are informed, is about 15 cwt. of umber to about 5 cwt. of 
Peruvian guano, from which an excellent-looking article, called African 
guano, is manufactured." — Liverpool paper. 



212 



YEARLY IMPORTATION OF GUANO. 



Years. 


Tons. 


Years. 


Tons. 


1841, 


2,881 


1847, 


82,000 


1842, 


20,398 


1848, 


n,414 


1843, 


3.002 


1849, 


83,438 


1844, 


104,351 


1850, 


116,925 


1845, 


283,300 


1851, 


. 245,016 


1846, 


89,203 







h. That the quantity huported in 1851 would sell for upwards 
of two millions sterling, and with good management ought to 
produce two or three times its own value in grain or other vege- 
table food. In other words, such a yearly supply of guano is 
equal to the importation of foreign grain and other produce to 
the value of from four to six millions sterling. 

c. It also serves as a stimulus, while it supplies one of the 
requisites, to the general introduction of improved methods of 
agricultural practice. 



CHAPTER XYI. 

Eelative theoretical values of different animal manures. — Chemical distinc- 
tion or difference between animal and vegetable manures. — Cause of this 
difference. — Effects of respiration. — Coldness of the droppings of the cow, 
and poorness of the manure from growing stock. — Improvement of the 
land by eating off' with sheep. 

SECTION I, OF THE RELATIVE THEORETICAL VALUES OF THE DIFFER- 
ENT ANIMAL MANURES. 

The fertilising power of animal manures, in general, is de- 
pendent, like that of the soil itself, upon the happy admixture 
they contain of a great number of those substances which are 
required by all plants in the universal vegetation of the globe. 
Nothing they contain, therefore, is without its share of influ- 
ence upon their general effects ; yet the amount of nitrogen 
present in each affords one of the readiest and most simple 
tests l)y which their relative agricultural values, compared 
with those of vegetable matters, and with each other, can be 
pretty nearly estimated. 

In reference to their relative quantities of nitrogen, there- 
fore, they have been arranged in the following order — the num- 
ber opposite to each representing the weight in pounds, which 
is equivalent to, or would produce the same sensible effect upon 
the soil as 100 lb. of farmyard manure: — 



Farmyard manure, 

Solid excrements of the cow, 

horse, 

Liquid excrements of the cow, 

horse. 

Mixed excrements of the cow, 

, horse, 

'■ sheep, 

pig, 



100 
125 
73 
91 
16 
98 
54 
36 
64 



214 RELATIVE VALUES OF ANIMAL MANURES. 

Dry flesh, . . _ ' . 3 

Pigeons' dung, .... 5 

Plemish liquid manure, . . 200^ 

Liquid blood, . . . . 15 

Dry blood, . * . . . 4 

Featliers, . . . . 3 

Cow hair, .... 3 

Horn shavings .... 3 

Dry woollen rags, . . . 21 

It is probable that the numbers iu this table do not err very 
widely from the true relative values of these different manures, 
in so far as the organic matter they severally contain is con- 
cerned. The reader will bear in mind, however — 

1. That the most powerful substances in this table, woollen 
rags for example — 2 J lb. of which are equal in virtue to 100 
lb. of farmyard manure — may yet show less immediate and sen- 
sible effect upon the crop than an equal weight of sheep's 
dung, or even of urine. Such dry substances, as I have said, 
are long in dissolving and decomposing, and continue to evolve 
fertilising matter, after the softer and more fluid manures have 
spent their force. Thus, while farmyard manure or rape-dust 
will immediately hasten the growth of turnips, woollen rags 
will come into operation at a later period, and will prolong 
their growth into the autumn. 

2. That besides their general relative value, as represented 
in the above table, each of these substances has a further spe- 
cial value not here exhibited, dependent upon the kind and 
quantity of the saline and other inorganic matters which 
they severally contain. Thus three of dry flesh are equal to 
five of pigeons' dung, in so far as the organic part is concerned ; 
but the latter contains also a considerable quantity of bone 
earth and of saline matter which is present only in minute 
quantity in the former. Hence pigeons' dung will benefit ve- 
getation in circumstances where dry flesh would in some degree 
fail. So the liquid excretions contain much important saline 
matter not present iu tlic solid excretions^ — not present cither 
in such substances as horn, wool, and hair — and, therefore, 



DIFFERENCE IN ANDIAL AND VEGETABLE MANURES. 215 

each must be capable of exercising an influence upon vegeta- 
tion peculiar to itself. 

Hence the practical farmer sees the reason why no one simj^k 
manure, such as hair or flesh, can long answer on the same land ; 
and why, in all ages and countries, the habit of employing mixed 
manures and artificial composts has been universally diffused. 
When mixed manures are not employed, the kind of manure 
which has been used must, after a time, be changed. A species 
of rotation of manures must, in fact, be introduced, in order 
that a second or third species of manure may give to the land 
those substances with which the first was unable to supply it. 

SECTION II. CHEMICAL DISTINCTION OR DIFFERENCE BETWEEN 

ANIMAL AND VEGETABLE MANURES. 

In what do animal manures differ from vegetable manures ? 
What is the cause of this difference ? How does the digestion 
of vegetable matter improve its value as a manure ? 

1. The characteristic distmctio7i hGUveen animal and vegetable 
manures is this — that the former contain a much larger 
proportion of nitrogen than the latter. This will be seen at 
once, by comparing together the tables given in the preceding 
pages, (184 and 212,) in which the numbers given represent 
the relative agricultural values of different vegetable and 
animal substances compared with that of farmyard manure. 
The lowest numbers represent the highest value, and the largest 
amount of nitrogen, and these low numbers are always opposite 
to the purest animal substances. 

2. In consequence of their containing so much nitrogen, 
animal substances are further distinguished by the rapidity with 
which, when moist, they putrefy or run to decay. During this 
decay, the nitrogen they contain gradually assumes the form of 
ammonia, which is perceptible by its smell, and which, when 
proper precautions arc not taken, is apt, in great part, to escape 
into the air. Hence the loss which occurs when manure is 



216 CAUSE OF DIFFERENCE BETWEEN THE MANURES. 

fermented too completely, or without proper precautions to 
prevent the escape of volatile substances. And as animal 
manure, when thus over-fermented, or permitted to give off its 
ammonia into the air, is, found to be less active upon vegetation 
than before, it is reasonably concluded that to this ammonia, 
and the compounds formed along with it, or to the substances 
from which they are produced, the ^peculiar virtue of animal 
manures, when rightly prepared, is in a great measure to be 
ascribed, 

Yegetable substances in general do not decay so rapidly, and 
emit little odor of ammonia when fermenting. When prepared 
in the most careful way, also, vegetable manure does not exhibit 
the same immediate and remarkable action upon vegetable 
growth as is displayed by almost every substance of animal 
origin. There are exceptions, indeed, to this general rule, since 
the crushed seeds of plants — rape-dust for example — produce an 
effect on many crops little inferior to that of animal manures. 
They, in fact, resemble animal substances very closely in their 
chemical composition. 

SECTION III.' CAUSE OF THE DIFFERENCE BETWEEN ANIMAL AND 

VEGETABLE MANURES. EFFECTS OF RESPIRATION. 

Whence do animal substances derive all this nitrogen ? Ani- 
mals live only upon vegetable productions containing little 
nitrogen ; can they then procure all they require from this 
source alone? Again, does the act of digestion produce any 
chemical alteration upon the food of animals so as to render 
their excretions a better manure, richer in nitrogen than the 
substances on which they feed ? Does theory throw any light 
upon the opinion generally entertained among practical men 
upon this point ? 

These two apparently distinct questions will be explained by 
a brief reference to one common natural principle. 

1. Animals have two necessary vital functions to perform — to 



EFFECTS OF ANIMAL DIGESTION. 21 1 

breathe and to digest. Both are of equal importance to the 
health and general welfare of the animal. The digester (the 
stomach) receives the food, melts it down, extracts from it those 
substances which are best suited to supply the wants of the 
bodj, and sends them forward into the blood. The breathers 
(the lungs) sift the blood thus mixed up with the newly-digested 
food, combine oxygen with it, and extract carbon — which car- 
bon, in the form of carbonic acid, they discharge by the mouth 
and nostrils into the air. 

Such is a general description of these two great processes ; 
their effect upon the food that remains in the body, and has to 
be rejected from it, is not difficult to perceive. 

Suppose an animal to be full grown. Take a full-grown man. 
All that he eats as food is intended merely to renovate or 
replenish his system, to restore that which is daily removed from 
every part of his body by natural causes. In the full-grown 
state, everything that enters the lody must come out of the body in 
one form or another. The first part of the food that escapes is 
that portion of its carbon that passes off from the lungs during 
respiration. This portion varies in weight in different individuals 
— chiefly according to the quantity of exercise they take. From 
6 to 9 ounces a-day is the average quantity given off from the 
lungs of a fulhgrown man, though in periods of violent bodily 
exertion, 13 to 15 ounces of carbon are breathed out in the 
form of carbonic acid. 

Suppose a full-grown man to eat a pound and a half of bread, 
and a pound of beef in 24 hours, and that he gives off by respi- 
ration 8 ounces of carbon (3500 grains) during the same time. 
Then he has 

Carbon. Nitrogen. 

Taken in his food, about 4500 grains, and 500 grains, while 



He has given off in res- \ 
piration, . . [ 



3500 and little or no nitrogen. 



Leaving to be converted \ 

into his own substance, >- 1000 grains and 500 grains. 
or to be re-jected, . ) 

10 



218 VALUE OF THE DUNG. 

Our two conclusions, therefore, are clear. The vegetable 
food, by respiration, is freed from a large portion of its carbon, 
which is discharged into the air, while nearly the whole of the 
nitrogen remains behind. In the food consumed, the carbon 
was to the nitrogen as 9 to 1 ; in that which remains in the 
body after respiration has done its work, the carbon is to the 
nitrogen in the proportion of only 2 to 1. 

It is out of this residue, rich m nitrogen, that the several 
parts of animal bodies are built up. Hence the reason why 
they can be formed from food poor in nitrogen, and yet be them- 
selves rich in the same element. 

It is this same residue also, which, after it has performed its 
functions within the body, is discliarged again in the form of 
solid and liquid excretions. Hence the greater richness in ni- 
trogen — in other Avords, the greater fertilising power possessed 
by the dung of animals than by the food on which they live. 

2. It must also be borne in mind, that the digested food con- 
tains all the saline matter, as well as nearly all the nitrogen, 
which had entered the stomach of the animal. Weight for 
weight, therefore, the dung must be richer also in saline matter 
than the vegetable food, and therefore i\iust be more fertilising 
in its effects upon the land. In an experiment made on the 
food and dung of the horse, it was found that while in the dry 
food the carbon was to the saline matter as 6 to 1, it was in 
the dry dung only as 2 to 1. 

3. Two other remarks I may here add, because of their 
interest to the practical man. 

a. The manure of the cow, taking it mixed, is not so rich in 
nitrogen as that of man. It is true that the cow, owing to its 
larger bulk and larger lungs, gives off perhaps eight or nine 
times as much carbon by respiration as an active full-grown 
man. But the weight of its daily food still farther exceeds that 
of a healthy man. Suppose the daily food of a cow to weigh 
ten times as much as the food we have supposed a man to eat, 
and to contain carbon and nitrogen in nearly the same propor- 



DUNG OF FULL-GROWN ANIMALS, 219 

tions — and that it gives off 60 ounces of carbon each day from 
its lungs — then we have 

Carbon. Kitrogen. 

In the food, . . 45,000 grains. 5000 grains. 

Given off by the lungs . 26,000 " . . " 

To be ultimately rejected, 19,000 " . 5000 " 

In the mixed manure rejected by such a cow, therefore, the 
carbon would be to the nitrogen in the proportion of about 4 
to 1 ; while in nightsoil it was, according to our former suppo- 
sition, as 2 to 1. Thus the mixed dung and urine of the cow 
is less rich as an immediately acting manure than the mixed 
nightsoil and urine of man. And since much of the nitrogen, 
as well as of the saline matter of the food, is contained in the 
urine of the cow, if this urine be allowed to escape, the solid 
cow-dung will be still colder and less fertilising. The dry mixed 
manure of the cow is richer in nitrogen than the dry food, 
weight for weight, but not so much so as if the cow gave off 
from her lungs a larger proportion of the carbon contained in 
her food. 

b. Since the parts of animals — their blood, muscles, tendons, 
and the gelatinous portion of their bones — contain much nitro- 
gen, young beasts which are growing must appropriate to their 
own use, and work up into flesh and bone, a portion of the ni- 
trogen contained in the non-respired part of their food. But the 
more they thus appropriate, the less w^ill pass off into the fold- 
yard ; and hence it is natural to suppose that the manure, either 
liquid or solid, which is prepared where many growing cattle 
are fed^ the food being the same, will not be so rich as that which 
is yielded by full-grown animals. This deterioration has actually 
been observed in practice, and it may with some degree of cer- 
tainty be expected in all cases to take place, unless, by giving 
a richer food to the young cattle, the difference to the farmyard 
is made up.* 

* Though I have dwelt as long upon these interesting, and, I believe, 



220 EATING OFF WITH SHEEP. 



SECTION lY. IMPROVEMENT OF THE LAND BY EATING OFF WITH 

SHEEP. 

The eating off with sheep is a practice on which some light 
is thrown by the considerations presented in the preceding sec- 
tion. This 'practice is adopted in different places with a view 
to very different objects. 

1. On sandy soils, as in Norfolk, the whole or part of the 
tnrnip crop is eaten off with sheep, for the purpose chiefly of 
treading down and consolidating the soil, and thus fitting it 
for the better growth of the succeeding crop of barley. The 
production of a mechanical effect upon the soil is here the chief 
tiling sought for, 

2. When the soil is not so light, the turnips are often eaten 
off with sheep for the sake of the regular and even manuring 
which the land is sure to obtain. The effect sought for here is 
also chiefly mechanical. The turnips could be drawn, and the 
dung collected, but it would afterwards have to be spread — and 
it could not by hand be so easily spread, or laid on the land so 
completely without loss. 

3. Independent of the above considerations, the general be- 
nefit to the land of eating off with sheep arises from the con- 
version of the vegetable produce into a manure richer, weight 
for weight, in nitrogen and saline matter, and, tlierefore, having 
a more immediate and powerful effect upon the after crops. In 
the case of land which is otherwise in good heart or condition, 
perhaps no better or more profitable husbandry than this, for 
rural districts, could readily be recommended. 

4. But the manure is richer, as we have seen, because the 
respiration of the animal separates a large proportion of the 

novel considerations, as the limits of this little work will permit, yet for 
fuller details, and for perhaps a clearer exposition of the principles above 
advanced, I must refer the reader to my Lectures on Agricultural Chemistry 
and Geology, 2d edition. 



EATING OFF AGAINST PLOUGHING IN. 221 

carbon which, the food contains. This fact throws light upon a 
question which the improving farmer has frequently asked him- 
self in reference .to poor or worn-out arable land, or to land he 
wishes to reclaim. If I sow a green crop — rape, or buckwheat, 
or rye, or tares-^had I better eat it off with sheep, or plough 
it in ? I am in doubt about the elfect of ploughing in, but 
I am sure that by eating off I shall give the land a good ma- 
nuring. 

Now theory answers this question distinctly. If the only 
object be to enrich the ground, plough in green. By this means 
the carbon is saved which would otherwise be dissipated by the 
lungs of the animal, — and this carbonaceous matter is of great 
value in improving poor, thin, or sandy soils, in which organic 
matter is deficient. 

But if enriching the soil be not the sole object— if some mut- 
ton also be desired — then it is good husbandry to eat off, with 
full-grown and fattening stock. The land will improve less 
rapidly in this way than by ploughing in, and it will be longer 
before you can safely crop it with corn, but it icill gradually 
improve under such treatment. 

Why fattening and not growing stock is to be kept on such 
land will appear from the considerations to be presented in the 
concluding chapter — on the feeding of animals. 



CHAPTER XV 11. 

Saline and mineral manures. — The salts of ammonia as manures. — Ammo- 
niacal liquor, sal-ammoniac, and sulphate of ammonia. — Results of expe- 
riments with these salts. — Quantity of nitrogen required by the wheat 
crop. — Carbonates, nitrates, a)id silicates of potash and soda. — Sulphates 
of potash and soda. — Common salt. — Sulphate of magnesia. — Sulphate of 
iron. — Gypsum. — Use of the phosphate and super- phosphate of lime, and 
cause of tiieir beneficial action. — Use of kelp, and of the ashes of wood, 
straw, the husk of oats, barle}'-, and rye, and of the sugar-cane. — Compo- 
sition and use of peat or Dutch ashes. — Coal ashes. 

The general nature and mode of operation of sucli saline and 
mineral substances as are capable of acting as manures, will be 
in some measure understood from what lias already been stated 
as to the necessity of nitrogen and of inorganic food to living 
plants, and as to the kind of inorganic food which they espe- 
cially require. It will be necessary, however, to advert briefly 
to the more important of these manures, — their use, their mode 
of action, and the theory of their observed effects. 

SECTION I. THE SALTS OF AMMONIA AS MANURES. 

The value of ammonia as a manure has been already spoken 
of (pages 27 and 52.) It exists in all fermenting animal ma- 
nures, and thus is constantly applied to the land even in the 
least advanced districts. There are several states, however, 
in which it has lately begun to be used, unmixed with other 
substances, and with manifest advantages to the crops. 

1. Ammoniacal Liquor. — This is water rich in ammonia, 
which is distilled from coal during the manufacture of coal gas. 
It is of various degrees of strength, and therefore, if applied to 
the land alone, it must be diluted with a variable proportion of 



CARBONATE OF AMMONIA. 223 

water. It often contains ammonia enough to yield, when satu- 
rated with spirit of salt, as much as a pound and a half of sal- 
ammoniac from a single gallon. That of the London gas- 
works is said to yield, when saturated with sulphuric acid, 
about 14 ounces of sulphate of ammonia from the gallon. 

To grass land this ammoniacal liquor may be appUed with 
great advantage, by means of a water-cart — being previously 
diluted with from three to five times its bulk of water. If too 
strong it will burn up the grass at first, especially if the wea- 
ther be dry; but, on the return of rain, the herbage will again 
spring up with increased luxuriance. 

On arable land it may be applied with profit to the young 
wheat or other corn by the water-cart, or it may be dried up 
by any porous material, and thus put into the turnip or potato 
drills. A friend in Northamptonshire writes me that the 200 
gallons of ammoniacal liquor per imperial acre, drunk up by 
sawdust and put into the drills, has alone given him an excel- 
lent crop of turnips. This manuring, however, cannot be ex- 
pected to keep the land in heart. A certain proportion of 
bone-dust should be mixed with this ammoniated sawdust, or 
else the corn crops should afterwards be top-dressed with rape- 
dust, guano, or bones. If, indeed, the land be already bom- 
sick, the saturated sawdust may be used alone, or Avith a mix- 
ture of wood or peat ashes for one rotation. 

The ammoniacal liquor may also be used advantageously to 
promote the fermentation of peat, sawdust, and other com- 
posts, — or it may be added to the ordinary dunghill, or to the 
liquid manure of the farmyard, and applied along with it to 
the laud. 

It is said to extirpate moss from old grass land more perma- 
nently than lime. 

2. Carbonate of ammonia is the common smelling salts of the 
shops. It exists in the ammoniacal liquor above described, and 
is very useful, in a diluted state, in promoting vegetation. It 
is too expensive, however, in the form in which it is at present 



224 STEEPING SEEDS IN SALTS OF AMMONIA. 

sold, to be of much use to the practical farmer. An oimce of 
it, dissolved in a gallon of water, gives a solution which 
destroys insects on rose-trees and other plants, and adds to their 
luxuriance at the same time. A few pieces laid on a plate and 
allowed to evaporate slowly into the atmosphere of a conserva- 
tory, are said to add greatly to the green and healthy appear- 
ance of the plants. 

3, Sal-ammoniac. — The same may be said of muriate of ammo- 
nia, the sal-ammoniac of the shops. Though experiment has 
shown that this substance exercises a very beneficial influence 
on the growth of our cultivated crops, yet the pure salt is too 
high in price to admit of its being economically used in ordinary 
husbandry. An impure variety, however, is prepared from gas 
liquor, which is sold at about 15s. a cwt, 

4, Sulphate of ammonia is now manufactured at a compara- 
tively cheap rate, and is sold at £16 a ton. This salt may be 
applied with advantage, especially to soils which are locally 
called deaf — which contain, that is, much inert vegetable matter, 
and to such as are naturally rich in phosphates. It may also 
be mixed with bones, rape-dust or wood-ashes, and put into the 
turnip or potato drills, or it may be used as a top-dressing in 
spring to sickly crops of corn. 

A case is mentioned of a field being manured for wheat, in 
part with ordinary farmyard manure, and in part with IJ cwt. 
per imperial acre (cost J£l*2s.) of sulphate of ammonia — when 
the produce of the former was 24, and of the latter 33 bushels 
per imperial acre. In other cases, also, it has been found a 
profitable application, both to young corn and to meadow hay. 

Faded flowers, when introduced into a solution of sulphate of 
ammonia, are said to be perfectly restored and revivified. 

5, Steeping of seeds in the salts of ammonia. — The salts of 
ammonia, especially sal-ammoniac and the sulphate of ammonia, 
have been strongly recommended as steeps for seed-corn. They 
have in many cases been found very advantageous in hastening 
germination, and in increasing the after luxuriance of the cKjp, 



EXPERIMENTS UPON WHEAT. 225 

Thus, in one experiment, seeds of wbeat, steeped in the sulphate 
of ammonia on the 5th of July, had by the 10th of August 
tillered into nine, ten, and eleven stems of nearly equal vigor, 
while unprepared seed had not tillered into more than two, 
three, or four stems. 

Sal-ammoniac has a similar effect. In Upper India it is pre- 
pared by heating together cAmel's dung and sea salt, and is used 
in the plains, among other purposes, for the steeping of seeds. 

It is to be observed, however, that neither when applied 
directly as a manure to the growing crops, nor when used as a 
steep for the seed, can the salts of ammonia alone bring a plant 
to maturity. .They tend to hasten its growth, if all its other 
wants can he readily supplied by the soil ; but if this is not the 
case, a quick decay will succeed to a short-lived luxuriance. 

SECTION II. RESULTS OF EXPERIMENTS WITH THE SALTS OF AMMONIA. 

NITROGEN NECESSARY TO THE WHEAT CROP. 

The last mentioned fact, as well as the general value of the 
salts of ammonia, is illustrated by the results of some experi- 
ments made by Mr. Lawes at Rothampstead in Hertfordshire. 
He sowed wheat for three successive years on the same piece of 
ground, applying only mineral manures the first year, and only 
ammoniacal manures the second and third years. The following 
were the results : — 

. ,. ,. . . , Produce. 

Application per imperial acre. ^^^^^^ g^^^^_ 

1844. Superphosphate of lime, 560 1b.) ^^ ^ j ^^^2 lb. 
Silicate of potash, - 220 ) 

1845. Sulphate of ammonia, ) ^^^^ ^, ^^,^_ 3^i _ ^266 .. 
Muriate of do. J 

1846. Sulphate of ammonia, 2 .. 27 .. 2244.. 

Thus upon a soil already rich in mineral manure, the applica- 
cation of salts of ammonia nearly doubled the crop of grain in 
1845, and quadrupled that of straw ; and, in 1846, added 
10* 



Z2f) NITRATES OF POTASH AND SODA. 

agam one-half to the grain above 1844, and doubled the straw. 
In each case, however, some allowance must probably be made 
for the influence of natural varieties in the seasons. 

As to the necessity of nitrogen to the wheat crop, Mr. 
Lawes concludes, from numerous experiments, that, ujpon his 
soil and in his locality, five pounds of ammonia — or four of ni- 
trogen, in some other available form — are '' required for the 
production of every bushel of wheat beyond the natural yield 
of the soil and the season."* But as a bushel of wheat con- 
tains only about 1 lb, .of nitrogen, (equal to 1^ lb. of ammonia,) 
it is obvious that, if this estimate be correct, the greater part 
of the nitrogen is lost to the farmer. The subject, therefore, 
is open to further investigation. 

SECTION III. SALTS OF POTASH, SODA, MAGNESIA, AND IRON. 

1°. Carbonate of fotash and soda.—^\\^ common pearl-ash, 
and the common soda of the shops, have not in this state been 
much employed in agriculture. Both, however, greatly pro- 
mote the growth of strawberries in the garden,- — and the latter 
is now cheap enough (10s. a cwt.) to admit of its being tried 
as a top-dressing on clovers and grass lands, on such as are old 
and mossy especially, with every prospect of advantage. It 
should be dissolved in much water, and put on with a water- 
cart, or thoroughly mixed with earth, and applied as a top- 
dressing. Mixed at the rate of one cwt. an acre, with bone or 
rape dust, or even with guano, it may be expected to improve 
both the turnip and the potato crops. 

Carbonate of soda, in the form of soda ash, has been applied 
with success to kill or to remove the effects of the wire-worm. 
It may either be sown with the wheat in winter, or applied as 
a top-dressing in the spring, to the affected wheat or oats. 

2°. Nitrates of j>otash and soda. — Saltpetre and nitrate of 

* Journal of Royal Agricultural Society of England, viii. 246. 



COMMON SALT. 22 1 

soda have been deservedly commended for tlieir beneficial ac- 
tion, especially upon youmg vegetation. They are distinguished, 
Hke the salts of ammonia, for imparting to the leaves a beautiful 
dark green color, and are applied with advantage to grass and 
young corn of any kind, at the rate of 1 cwt. to 1^ cwt. per 
acre. They are said even to benefit young fir-trees. Applied 
to young sugar-canes they have been found largely to increase 
the crop, and even, in the second year after their application, 
to add much to the luxuriance of the cane fields. The nitric 
acid they contain yields nitrogen to the plant, while potash and 
soda are also put within reach of its roots, and no doubt serve 
many beneficial purposes. Upon land rich in phosphates, ni- 
trate of soda is a profitable application to wheat, being found, 
in Norfolk, to return an Increase of from 4 to 1 bushels of grain 
for every cwt. applied to the corn in spring.* It is especially 
recommended for wheat, on hght, gravelly, and sandy soils, and 
on cold undrained clays. 

3°. Sulphate of potash is likely to be useful, especially to 
root and leguminous crops. Its price, however, is usually high, 
varying from £\% to £20 a ton. 

4°. Common salt has, in many districts, a fertilising influence 
upon the soil. It destroys small weeds; improves the quality 
of pastures, and renders them more palatable ; strengthens and 
brightens the straw, and makes the grain heavier per bushel, 
both of wheat and oats. It has been observed, also, to pro- 
duce specially good effects upon mangold-wnrtzel. 

A small quantity of salt is absolutely necessary to the healthy 
growth of all our cultivated crops, but it is in inland and shel- 
tered situations, and on high lands often washed by the rains, 
that its effect is likely to be most appreciable. The spray of 
the sea, borne to great distances by the winds, is in many dis- 
tricts, where prevailing sea winds are known, sutficient to sup- 
ply an ample annual dressing of common salt to the land.f 

* See the Author's Lectures on Agricultural Chemistry, 2d edition. 
f At Penicuik, near Edinburgh, the rain that falls contains so much com- 
mon salt as alone to convey 640 lb. to every acre in a year. — (Dr. Madden-") 



228 SULPHATES OF MAGNESIA AND IRON. 

It has sometimes been found to be of still more advantage, 
in strengthening the straw, to apply a mixture of quicklime 
with a fourth or a fifth part of its weight of dry salt; or the 
salt may be dissolved in water, and the lime heap slaked with 
the solution — or sea water may be at once employed to slake 
the lime. 

5°. Sulphate of soda, or Glauber's salt, has lately been re- 
commendetl in this country for clovers, grasses, and green crops. 
Mixed with nitrate of soda it produces on some soils remarka- 
ble crops of potatoes, and in some localities, when used alone, 
it has greatly benefited the turnip crop. Mr. Girdwood found 
that li cwt. of this sulphate per acre, sprinkled upon the other 
manure in the drills, added 16 bushels an acre to his crop of 
beans. It is on rich land only, however, that the addition of a 
single saline substance can be expected to produce results so 
favorable as this. 

6°. Silicates of jpotash and soda. — When potash and soda are 
melted together with silicious sand, they form a kind of glass 
which is soluble in water. This has produced remarkable 
effects upon the potato crop, and, like other silicates, is recom- 
mended as a strengthener of the straw of our corn crops. 

^°. Sulphate of magnesia, or Epsom salts, is also beneficially 
applied in agriculture to clovers and corn crops. It can be had 
in pure crystals at 10s. a cwt., and in an impure state at from 
3s. to 6s. a cwt. It has been found of advantage as a top- 
dressing for the young wheat, and as an application to the 
potato. Where the soil is deficient in magnesia, it may always 
be expected to improve the crops of corn. 

8°. Sulphate of iron. — Common green vitriol, applied in the 
form of a weak solution, has been observed to strengthen feeble 
plants, and to give them a brighter green. It has also been 
used as a top-dressing for grass, and as an application to dis- 
eased fruit trees. It deserves a further trial 



GYPSUM AND OTHER SULPHATES. 229 



SECTION IV. USE OF THE SULPHATE AND PHOSPHATES OF LIME, AND 

CAUSE OF THEIR BENEFICIAL ACTION. 

1°. Sulphate of liiiie, or gypsum, is in Germany applied to 
grass land with great success, and over large tracts of country. 
In the south of England it has been applied to some grass lands 
with benefit for thirty-five years in succession, at the rate of 2 J 
cwt. per acre. It supplies the lime and sulphuric acid annually, 
which are annually removed by the crop. In the United States 
it is used for every kind of crop ; and I have there seen it pro- 
duce very striking effects on Indian corn. It is especially 
adapted to the pea, the bean, and the clover crops. It is more 
sensibly efficacious when applied in the natural state than after 
it is burned. 

The sulphates all afford sulphur to the growing plant, while 
the lime, soda, magnesia, &c., which they contain, are themselves 
in part directly appropriated by it, and in part employed in pre- 
paring other kinds of food, and in conveying them into the 
ascending sap. 

Though there can be no question that these sulphates, and 
other similar substances, are really useful to vegetation, yet the 
intelligent reader will not be surprised to find, or to hear, that 
this or that mineral substance has not succeeded in benefiting 
the land in this or that district. If the builder has already 
bricks enough at hand, he needs mortar only, to enable him to 
go on with his work : so, if the soil contain gypsum or sulphate 
of magnesia in sufficient natural abundance, it is at once a need- 
less and a foolish waste to attempt to improve the land by add- 
ing more ; it is still more foolish to conclude, because of their 
failure in one spot, that these same saline compounds are unlikely 
to reward the patient experimenter in other localities. 

2°. Phosphates of lime. — a. Burned bone. — When bones are 
burned in an open fire, they diminish in weight about one-half, 
and leave behind a white earthy matter long known by the name 



230 ACID OR SULPHATE OF LIME. 

of hone earth. This bone earth consists chiefly of j)hosjphafe of 
lime (page 193.) 

Bones are known to be an excellent manure, and as our cul- 
tivated crops, and especially our corn crops, contain much phos- 
phoric acid, it has been justly concluded that part of their eifect 
is due to the bone earth they contain. Hence the use of burned 
bones as a manure has been warmly recommended. 

In soils which are poor in phosphate of lime, there is no doubt 
but burned bones will be likely to benefit the crops of corn ; 
but there are few soils, I think, in which a ton of bone-dust 
would not produce a better effect than the ash left by an equal 
weight of bones. 

h. Native jihosjphate of lime. — Phosphate of lime is found as 
a native mineral in many countries, and has been applied with 
advantage to the soil. It has lately been met with in the States 
of New York and New Jersey in sufficient quantity to make it 
likely to prove a profitable article of import into this country. 
It has also been discovered in considerable quantity in the marls 
of the crag and green-sand formations (see p. 94,) of England, 
and is now dug up in large quantities for agricultural purposes.* 
In our ordinary limestones it also exists in variable quantity. 
In a burned lime from Carluke, which is full of fossils, I have 
found it to the extent of 2| per cent ; so that every ton of such 
lime conveys to the land as much phosphate of lime as two 
bushels of bones. This must modify in a favorable manner the 
effect of such lime when applied to the land. 

c. Acid or sujper-jphosjphate of lime. — When burned bones are 
digested with sulphuric acid diluted with three times its bulk of 
water, gypsum (sulphate of lime) is produced, and falls to the 
bottom of the solution, while the phosphoric acid, and a portioii 
of the lime, remain in the sour liquid above it. When this 
liquid is boiled down or evaporated to dryness, it leaves a white 
powder, which is known by the name of acid or super-phosphate 

* Journal of the Royal Agricultural Society, vol. ix. p. 56, and vol. xii. p. 93. 



ASHES OF SEA-WEED, WOOD AND STRAW. 



231 



of lime. Under the latter name it has been introduced into the 
manure market. It is extensively manufactured in this country, 
by grinding the mineral phosphate obtained from the crag of 
Norfolk and Suffolk, (p. 93,) mixing it with about an equal 
weight of strong suli)huric acid, and then drying the whole. 
Some manufacturers mix a portion of bone dust with the mine- 
ral powder, and thus produce a manure containing some animal 
matter, and therefore of more general utility. 

As the ordinary burned bones are difficult to dissolve in the 
soil, and as the acid phosphate is more easy of solution, it is 
likely to be taken up more readily by the roots, and thus more 
rapidly to aid the growth of plants. These super-phosphates 
are sold at present at about £7 a ton. 

Numerous experiments have been made with the super-phos- 
phate, and very remarkable results have been obtained by its 
use, chiefly as a manure for the turnip crop, but also as a top- 
dressing for grass, and for wheat, and other kinds of corn. 
What is sold as super-phosphate by the manufacturers, is very 
variable in its composition, and is often largely adulterated. 

SECTION v.— OF THE ASHES OF SEA-WEED, WOOD, STRAW, THE HUSK 
OF OATS, BARLEY, AND RICE, AND OF THE SUGAR-CANE. 

1. Kdj> is the ash left by the burning of sea-weed. It con- 
tains potash, soda, lime, silica, sulphur, chlorine, iodine, and 
several other of the inorganic constituents of plants which are 
required by them for food. It is nearly the same also— with 
the exception of the organic matter which is burned away— 
with the sea-weed which produces such remarkably beneficial 
effects upon the soil. In the Western Isles a method is prac- 
tised of half-burning or charring sea-weed, by which it is pre- 
vented from melting together, and is readily obtained in the 
form of a fine black powder. The use of this variety ought to 
combine the beneficial action of the ordinary saline constituents 
of kelp, in feeding or preparing food for the plant, with the 



232 LIXIVIATED WOOD AND STRAW ASHES. 

remarkable properties observed in animal and vegetable char- 
coal. In Jersey, the sea-weed is dried and burned in the 
kitchen grates, and the ash is considered to be efficacious in 
destroying grubs. In the Orkneys, potatoes are ^ raised by 
means of a mixture of peat ashes and kelp, applied at the rate 
of fifty bushels to the Scotch acre. 

2. Wood ask contains, among other substances, a portion of 
common pearl ash in an impure form, mixed with sulphate and 
silicate of potash. These substances are all valuable in feeding 
and in preparing the food of plants, and hence the extensive 
use of wood ash as a manure in every country where it can 
readily be procured. Wood ash, applied alone, is especially 
beneficial to clovers, beans, and other leguminous plants. Mixed 
with bones in nearly equal bulk, it is extensively employed in 
this country as a manure for turnips. In some soils it has been 
found, without any admixture, to raise large crops of potatoes. 
In Persia, seed wheat and melon seeds are always steeped, for 
24 hours before sowing, in a ley of wood ashes. In Lower 
Canada, 40 bushels of wood ashes applied alone, give a crop of 
200 to 250 bushels of potatoes. 

3. Lixiviated tvood ash. — When the common wood ash is 
washed with water as long as any thing dissolves, and the solu- 
tion is then boiled to dryness, the common potash of commerce 
is obtained. But a large portion of the ash remains behind un- 
dissolved, and in countries where much wood is burned for the 
manufacture of potash, this lixiviated or washed refuse accumu- 
lates. It consists of silicate of potash mixed with silicate, 
phosphate, and carbonate of lime, and when applied to the 
land is remarkably favorable to oats. It suits better for clay 
lands, and when laid on in considerable quantity, (1 or 2 tons 
to the acre,) its effects have been observed to continue for 15 
or 20 years. (Sprengel.) 

4. Straw ashes. — In this country straw is seldom burned for 
the ash. In Germany, rye-straw is not unfrequcntly burned, 
and the ash employed as a top-dressing. The dry straw is 



ASHES OF OATS, BARLEY, RICE AND CANE HUSKS. 233 

strewed over the field, tlien burned, and the ash ploughed in on 
the spot. In many countries — among others, in some parts of the 
United States — the straw is often burned, and the ash scattered 
to the wind. When it is too much trouble to ferment the 
straw in the farmyard, labor might surely be spared to strew 
the £tsh upon the fields from which the crop was taken. The 
soil would not fail to give a grateful return. 

5. Ash of the- husk of oats, harley, and rice. — The hush, seeds, 
or shellings of oats or barley, being supposed to contain no 
nourishment, are often burned for the purpose of heating the 
kiln on which the grain is dried. When thus burned, these 
husks leave a considerable quantity of a white or. grey ash. 
The oat husk I find to leave about 5 J per cent of its weight. 
This ash has hitherto been neglected by the millers, being ge- 
nerally thrown into the stream by which their mills are worked. 
It should, however, be carefully preserved. It may be ex- 
pected to prove a valuable top-dressing to meadow land, to 
young corn crops, and especially to bog oats. One miller in 
the north of Scotland informs me that he makes about two 
bushels a day of ash from the husk of the oats he grinds. The 
waste of this ash, long persevered in, can scarcely have failed 
slowly to impoverish the adjoining land. 

In China, India, and other countries where rice is grown, 
the husk of this grain also is burned; but the ash is rarely 
afterwards returned to the soil. In China, it is said to be em- 
ployed in the making of certain articles of manufacture. 

6. Cane ash. — The sugar-cane when brought from the mill in 
the state of trash, is burned for the purpose of boiling down 
the syrup. The ash left by it is rich in those saline substances, 
without which the cane cannot thrive. Without having per- 
sonally examined any of our West India plantations, I may 
safely hazard the opinion that some, at least, of the exhaustion 
complained of by the planters is owing to the neglect of this 
valuable ash — and that the large importation of foreign ma- 
nures, now -had recourse to, might by and by be in some mea- 



234 PEAT ASHES FROM PAISLEY. 

sure dispensed with, by carefully collecting, grinding, and 
returning it to tlie soil. 

SECTION VI. COMPOSITION AND USE OF PEAT OR DUTCH ASHES. 

COAL ASHES. 

Peat or Dutcli ashes are the ashes of peat burned for the 
purpose of being applied to the land. They vary in composi- 
tion with the kind of peat from which they have been prepared. 
They often contain traces of potash and soda, and generally a 
quantity of gypsum and carbonate of lime, a trace of phos- 
phate of hme, and much silicious matter. In almost every 
country where peat abounds, the value of peat ashes as a ma- 
nure has been more or less generally recognised. The following 
analyses of two samples of such ashes from the Paisley moss, 
and of two from the island of Lewis, all examined in my labo- 
ratory, show how valuable, and, at the same time, how very 
different in quality, such ashes may be, even when they are ob- 
tained from the same locality. 

a. Ashes from the Paisley moss. 









White Peat 


Black Peat 








Ashes. 


Aslies. 


Charcoal, 


- 


- 


54.12 


3.02 


Sulphates and carbonates of potasli, 




soda, and magnesia, 


- 


- 


6.5Y 


5.16 


Alumina, 


- 


- 


2.99 


2.48 


Oxide of iron, 


- 


- 


4.61 


18.66 


Sulphate of lime, - 


- 


- 


10.49 


21.23 


Carbonate of ditto. 


- 


- 


8.54 


3.50 


Phosphate of ditto, 


- 


- 


0.90 


0.40 


Silicious matter, 


- 


- 


10.88 


43.91 



99.10 98.3G 



It will be observed that the first of tliese contained more 
than half its weight of unburncd charcoal, and still was richer 
than the other, weight for weight, both in soluble salts and in 
phosphate of lime — two of their most valuable ingredients. 



PEAT ASHES FROM LEWIS. 235 

The reason of this is, that the white peat, being nearer the 
surface, consists of vegetable matter less decomposed. The 
ashes of the upper layers of peat, therefore, will generally be 
more valuable than those of the under layers. _ 
h. Ashes from the island of Lewis. 



0.29 
6.51 



Chloride of sodium, (common salt,) 0.41 

Phosphate of lime, - - - 2.46 

Sulphate of iime, (gypsum,) - - 28.66 16.85 

Sulphate of magnesia, - - 1.68 2.01 

Magnesia ) in state of silicate ( ^.f^ ^^^ 

, Potash. .d soda, J ,,, ,,rhonate, | ,f,^^ \f. 

Oxide of iron, - - - 9.18 6.58 

Silica, soluble in caustic potash, - 15.55 28.58 

Insoluble silicious matter and sand, - 7.94 14.20 

Carbonic acid, charcoal, and loss, - 10.85 7.99 

100. 100. 

These samples, again, present other differences. They con- 
tain, in addition to the alkaline matter and the gypsum, a more 
considerable proportion of phosphate of lime than the others. 
In the one, the phosphate amounts to 6| per cent, and must 
contribute materially to its fertilising value. The soluble silica 
is also deserving of notice, as likely to be useful — especially to 
grass land and to crops of corn. 

Peat ashes are not unfrequently used alone, and with 
success, for the raising of turnips. Much of their success, 
however, will depend on the peculiar composition of the ashes 
employed. 

In Lancashire, peat only half burned is considered preferable 
to double the quantity burned to a perfect ash. 

Coal ashes consist in general of alumina and silica mixed 
with a variable proportion of gypsum, carbonate of lime, phos- 
phate of lime, and oxide of iron, mixed with half-burned coal. 
They vary, however, with almost every different kind of coal 
that is burned. 



CHAPTER XYIII. 

Why saline manures are required by the soil. — Mode of determining their 
local value. — Circumstances necessary to insure the successful application 
of saline manures. — Of saline manures which exercise a special or specific 
action upon plants. — Results of experiments with mixed saline maniires, 
made with the view of increasing the crop or of affecting its quality. — 
Artificial mixtures in imitation of valuable natural manures. — Recipe for 
artificial g^uano. 



SECTION I. WHY SALINE MANURES ARE REQUIRED BY THE SOIL. 

The use of saline substances as manures is of comparatively 
recent introduction. In many districts, however, they are indis- 
pensable, , if we wish to maintain the present condition, or to 
restore the ancient fertility of the land. This will appear from 
the following considerations : 

1. These saline substances exist in all plants, and must there- 
fore abound, to a certain extent, in all soils in which plants can 
be made to grow. 

2. The rains gradually wash out from the surface — especially 
of undrained arable soils, and in inland districts — a portion of 
the saline matter they contain. If the surface soil is to be 
retained in its present condition, this natural waste must, by 
some means or other, be supplied. 

3. The crops we carry off the land remove also a portion of 
this saline matter from the soil, and thus gradually impoverish 
it, if the saline substances be not again brought back. 

4. And though we return to the soil, in the form of farmyard 
manure, all the straw of our corn crops and the dung of our 
cattle, land still loses all that we carry to market, and all that 
escapes from our farmyards and dung-heaps in the form of liquid 



LOCAL VALUE OF SALINE MANURES. 23t 

manure. Even where tanks for liquid manure are erected, the 
farmer can never return to the land all the saline substances 
contained naturally even in his straw. The rains that fall, were 
there no other cause of waste, would wash away some portion 
of what he would desire to carry back into his field. 

The necessary waste of saline matter, arising from the above 
causes, must be supplied from some source or other. When, for 
a long period of time, the land has maintained its fertility with- 
out receiving any artificial supply, it must contain within itself 
naturally a very large proportion of these substances — must 
derive from springs a continued accession of such matter, or 
from waters that flow down from a higher level and bring with 
them the washings of the upper soils — or it must obtain from 
abundant sea-spray a sufficiency to supply the wants of the 
plants that grow upon it. 

The practical man will readily acknowledge that, when a suffi- 
ciency of saline matter is not conveyed to his land from these 
or similar sources, he must necessarily supply it by art. He 
will understand, also, that the saline manures he adds to' the soil 
operate by yielding to the plant what it could not otherwise so 
readily obtain ; and that a saline substance which has been 
found to benefit his neighbor's land, may happen, when applied, 
to do no good to his own — because his own may already con- 
tain a sufficient supply of that substance. 

SECTION II. MODE OF DETERMINING THE LOCAL VALUE OF SALINE 

MANURES. 

In order, therefore, to determine whether his land will rea- 
dily be benefited by the application of those saline substances 
from which, in other districts, or upon other soils, much benefit 
has been derived, the intelligent farmer will commence a series 
of preliminary trials or small experiments. 

That many of the saline substances described in the preced- 
ing Sections maybe projitahly applied to most soils by the prac- 



238 VALUE OF SALINE MANURES. 

tical farmer, can no longer be doubted. At the same time, no 
prudent man will at once expend any large sum upon them, 
until either he himself, or some of his immediate neighbors who 
cultivate a similar soil, have previously proved their efficacy on 
a smaller scale. It is no doubt the duty of every practical 
farmer — a duty he owes not only to his country but to himself 
— to be alive to the benefits which are to be derived from every 
improved method of culture that may be introduced ; but it is 
no less his duty to avoid every reasonable risk of pecuniary 
loss which might be injurious to himself. 

Suppose, therefore, I were to enter upon a farm which I was 
desirous of rendering as productive as possible, by the applica- 
tion of every new manure, or every new method of culture that 
might prove to be suited to the kind of soil I possessed, I 
would begin by trying the effect of each manure or method 
upon a single acre, and I would extend my trials or alter my 
methods according to the success I met with. 

Among saline manures, for example, I would try nitrate of 
soda, or carbonate of soda, or wood ashes, or sulphate of soda, or 
common salt, or silicate of soda, or gypsum, or sulphated urine, or 
guano, or the ammoniacal salts, or the soluble phosphates, or a 
mixture of two or more of these substances, on a single acre or 
half acre of my various crops — never expending in this way, during 
any one year, more than I could easily afford to lose if my trials 
should fail ; and I would not begin to use any of these sub- 
stances largely till I was satisfied that there was a reasonable 
prospect of remuneration. And having once begun upon this 
assurance, I would cease applying them for a while as soon as 
the crops no longer gave me a fair return for my outlay — the 
probability then being, that the soil for the present had ob- 
tained enough of the peculiar substance I had been employing, 
and stood more in need of some other. 

Thus if, as happened to a friend of mine, a dressing of salt 
was followed by a produce of 35 bushels from the first wheat 
crop, and yet, when applied to the next crop of the same grain 



CIRCUMSTANCES NECESSARY TO SUCCESS. 239 

on the same field, the yield was only 20 bushels, I should con- 
clude that, for the present, my land was sufficiently salted, and 
that I had better apply something else. I would therefore 
begin my experiments anew upon my salted land. I would try 
some of the other substances above named, employing always 
the same caution and economy as before, and carefully keeping 
an account of my procedure, and of my profit and loss from 
each experiment. 

Such facts, also, as that in the State of Xew York, after a 
long-continued use of gypsum, the employment of leached or ex- 
hausted wood ashes (p. 233) was found to be more beneficial, 
woTild incline me to make many trials of such variations or ro- 
tations of manures. 

I should thus have always several experimental patches upon 
my farm ; and I should not only avoid the risk of serious disap- 
pointment and pecuniary loss, but I should enliven my ordinary 
farm routine by the interest I should necessarily feel in watch- 
ing the results of my different experiments — I should gradually 
acquire habits of reflection, and of careful observation also, 
which would be of the greatest possible service to me in all my 
future operations.* 

SECTION III. OF THE CIRCUMSTANCES WHICH ARE NECESSARY TO 

INSURE THE SUCCESSFUL APPLICATION OF SALINE MANURES. 

The application of saline substances to the soil is not always 
attended with sensible benefit to the crop. Th§ same substance 
which, in one district, or in one season, has produced an increased 
return, may fail in another district or in a different season. The 
circumstances which are necessary to insure success in the appli- 
cation of saline manures are chiefly the following : — 

1°. They must contain one or more of those substances which 

* For numerous suggestions as to such experiments, I would refer the 
reader to my pubUshed ExpeTimcntal Agriculture — a work entirely devoted 
to the subject of rural experiments. 



240 SUBSTANCES EXERCISE A SPECIAL ACTION 

are necessary to the growth of the plant, and in a condition or 
state of combination in which the plant can take them up. 

2°. The soil must be more or less deficient in these substances. 

3°. The weather and soil must be moist enough to admit of 
their being readily dissolved and conveyed to the roots, or the 
land must be artificially irrigated. 

4°. They must not be applied in too large a quantity, or 
allowed to come in contact with the young shoots in too con- 
centrated a form. The water th-at reaches the roots or young 
leaves must never be too strongly impregnated with the salt, or, 
if the weather be dry, the plant will be blighted or burned up. 

5^. The soil must be sufficiently light to permit the salt easily 
to penetrate to the roots, and yet not so open as to allow it to 
be readily washed away by the rains. In reference to this 
point the nature of the subsoil is of much importance. A re- 
tentive subsoil will prevent the total escape of that which 
readily passes through a sandy or gravelly soil ; ivhile a very 
open subsoil, again, may retain little or nothing of what has 
once made its way through the surface. 

6°. I may add, lastly, that it is in poor or worn-out soils that 
all such applications may be expected to produce the most 
marked and characteristic effects. 



SECTION IV. OF SALINE MANURES WHICH EXERCISE A SPECIAL OR 

SPECIFIC ACTION UPON PLANTS. 

An interesting branch of the present part of our subject is 
the use of what are called special manures. Certain substances 
have been observed to exercise a special action. 

1. Ujpon all 'plants. — ^Thus, the salts of ammonia promote 
the growth, or prolong the green and growing state of most 
plants. Nitrate of soda has a similar effect — while the addition 
of lime to the soil, especially in well-drained and high lands, 
almost uniformly hastens the ripening of the seed, and produces 
an earlier harvest. 



ON DIFFERENT KINDS AND PARTS OF PLANTS. 241 

2. On particular parts of plants ; — as when the gardener 
improves his roses by mixing manganese with the soil, reddens 
his ornamental hyacinths by putting carbonate of soda into the 
water in which they grow — or by other substances, as by the 
acid or 5Wj?e/--phospliate of soda, attempts to vary the hue or 
bloom of his cultivated flowers. This principle is attended to 
in practical agriculture, when substances are mixed with the 
manure, which are believed to be specially required by the stalk 
of corn, where a field produces a defective straw — or by the 
ear, where the grain refuses to fill. The application of silicate 
of potash, of soda, or of lime, to the soil may add strength to 
the straw, while the phosphates fill the ear, or bring it to ear- 
lier maturity — as carbonate of potash, according to Wolff, pro- 
motes the growth of the leaves and stems of the vine, while the 
phosphates develop the fruit. 

3. On particular kinds of plants. — Farmyard manure rarely 
comes amiss to any soil or any crop; but gypsum exercises a 
peculiar action upon red clover; while wood-ashes, lime, and 
other alkaline manures, cause white clover to spring up sponta- 
neously, where it had before refused to grow even when sown. 
So lixiviated wood ashes are favorable to oats; ammonia, or 
the nitrates, are by some regarded as the peculiar manures for 
wheat; phosphate of magnesia has been extolled as a specific 
for potatoes ; and superphosphate of lime for our British turnip 
crops. 

All such facts as these are exceedingly valuable. Many of 
the alleged specifics, however, are only locally so. Thus bones, 
which produce such wonderful effects in Great Britain, espe- 
cially upon turnips and upon some old grass lands, as those of 
Cheshire, are much less conspicuously effective in some parts of 
Germany, and even of our own island ;* while gypsum, so 
much and so generally prized by the German and American 
farmer, is more rarely found to answer the expectations of the 
English agriculturist. 

* On some of the soils of the green-sand, for example. 
11 



242 RESULTS OF EXPERIMENTS 

The truth is, that if the crop we wish to raise specially re- 
quires any one substance which is not present in sufficient quan- 
tity in the soil, that substance will there prove a specific for 
that crop ; while, in another soil in which it is already abun- 
dantly present, this substance will produce little beneficial ef- 
fect. Failures, therefore, may every now and then be expect- 
ed in the use of so-called specific manures, the evil of which is 
not limited to the immediate loss experienced by the incau- 
tious experimenter. They serve also to dishearten those who, 
through their much faith, have been disappointed in their ex- 
pectations, and thus to retard the progress of a truly rational 
experimental agriculture. 

SECTION V, RESULTS OF EXPERIMENTS WITH MIXED SALINE MA- 
NURES, MADE WITH THE VIEW OF INCREASING THE QUANTITY OF 
THE CROP. 

The same remark applies also to artificial mixed manures, 
when held forth as specifics for any or for all crops on every 
soil. The animal and vegetable manures which occur in na- 
ture, are all mixtures of a considerable number of different 
substances, organic and inorganic. We are imitating na- 
ture therefore, and are in reality so far on the right road, 
when we compound our artificial mixtures. The soil may be 
deficient in two, three or more substances ; and to render it 
fertile, it may be necessary to add all these ; while, if it be de- 
fective in one only, we are more likely to administer the right 
one, if we add a mixture of several at the same time. It is 
safer and surer, therefore, to add a mixture of several saline 
substances to our soils. 

There are only two ways, however, in which we can safely 
make up mixtures .that are likely to be useful — either by actual 
experiment upon the kind of land we wish to improve, or by an 
exact imitation of the procedure, and })y attention to the re- 
quirements, of nature. 



WITH MIXED SALINE MANURES. 24S 

1. Mixture of nitrate u-ith sid'phate of soda. — In 1840 I re- 
commended the trial of sulphate of soda (Glauber's salts) as a 
manure, and in 1841, Mr. Fleming of Barochan, besides mak- 
ing an experiment with the sulphate alone, tried a mixture of it 
with nitrate of soda in equal weights — adding 1| cwt. of the 
mixture to the acre. The effect of this mixture as a top-dress- 
ing upon potatoes was extraordinary. T/ie stems were six and 
seven feet in length, and the 'produce upward of 30 tons per impe- 
rial acre. In 1842, tried on a larger scale, the produce was 
not so extraordinary ; but, though a very dry season, the pro- 
duce was 18 tons per acre of early American potatoes ; while 
the dung alone, 40 cubic yards per acre, gave less than 13 tons. 
These results are sufficiently striking to justify the reader in 
trying this mixture on any soil. If his fields be like the land 
of Mr. Fleming, the trial may prove eminently successful ; if 
different in physical character or chemical composition, or if 
the season be unpropitious, the result may be less favorable. 
A mixture, though it succeed in the hands of fifty experiment- 
ers, will still not be entitled to be considered as a specific. It 
must first be found never to fail. 

The cost of this mixture, as applied per acre, was at that 
time as follows : — 



•75 lb. nitrate of soda, at 22s. per cwt. . . . £0 14 9 
75 lb. dry (uncrystallised) sulphate of soda, at 9s., 6 3 



[about $5 25] 1 1 

The increased produce from this application — strewed about 
the young plants when they came above ground — was 8 tons 
per acre in 1841, and 5 tons per acre in 1842. 

2. The superior effect of mixtures above that of the substances 
they contain when employed singly, is shown in an interesting 
manner by the following results, obtained by the same experi- 
menter : — 

An entire field was manured for potatoes with 40 cubic yards 



244 MIXED SULPHATES AND NITRATES. 

of dung, and when the potatoes — early Americans — were a few 
inches above the ground, different measured portions of the 
field were top-dressed with different saline substances, with the 
following results per imperial acre : — 

Tons. 

Dung alone gave . . . . 12| - 

. . with 2 cwt. sulphate of soda, . . 12| 

1 5 cwt. nitrate of soda, . . 16 

1 4 cwt. sulphate, ) _• ^j to 

T , ..^ . ' y mixed, . lo 

I cwt. nitrate, J ' 

Here, though the sulphate alone produced no increase, it 
materially augmented the effect of the nitrate when the two 
were applied together. 

3. Sulphate of soda with sulphate of ammonia. — Again, on 
the same field on which sulphate of soda, applied alone, gave 
no increase, 

Tons. 
1^ cwt. sulphate of ammonia alone gave only . lij 
While n cwt sulphate of soda, and ) ^. ^g^ 

I cwt. sulphate of ammonia, ) ' ^ 

Being an increase of 6 tons an acre above sulphate of soda, 
and 4 tons above sulphate of ammonia applied alone. 

4. Nitrate of soda with sulphate of magnesia. — Also on the 
same field, while 

Tons. 
I5 cwt. of nitrate of soda gave, as above, onlj . 16 
And 1 2 cwt. of sulphate of magnesia, only . . 134 

1 cwt. of each, mixed together, gave . . 22 J 

Thus experiment, as well as theory, indicates that the appli- 
cation of several saline substances mixed together, is more likely to 
increase the produce of the soil than a larger addition of either 
applied alone. 

5. Phosphate of 7nagnesia with phosphate of ammonia.- — I have 
said that attention to the requirements of nature will indicate 



EXPERIMENTS WITH MIXED PHOSPHATES. 245 

what mixtures m^ be tried wifh the hope of success, and even 
what mixtures may be likely to prove specific manures. Thus 
it is known from analysis that the seeds of plants — the grain of 
our corn crops for example — contain much nitrogen in their 
gluten, and that the ash of grain is rich in phosphoric acid and 
magnesia. It was natural to suppose, therefore, that the appli- 
cation to growing corn of a mixture capable of specially sup- 
plying these three substances would specially act in filling the 
ear. A saline compound known by the name of phosphate of 
magnesia and ammonia, containing the two phosphates united,* 
is fitted for this purpose, and was consequently recommended 
for trial. 

Experiments, recently made, show that it exercises a power- 
ful influence, especially upon Indian corn. Applied at the rate 
of 130 to 260 lb. per acre, it had also a very favorable, though 
less marked, influence upon wheat. Upon Indian corn, at the 
rate of 3 cwt. per acre, it increased the crop of grain six times, 
and of straw three times. A constant effect is to increase the 
weight of the grain per bushel as common salt does; and, like 
many other substances, it produces most marked effects upon 
poor and worn-out soils. 

This compound, therefore, is deserving of further trial ; and 
it is desirable that attempts should be made to manufacture it 
for the manure-market at a moderate price. f 



SECTION VI. RESULTS OF EXPERIMENTS WITH MIXED SALINE MA- 
NURES MADE WITH THE VIEW OF AFFECTING THE CHARACTER OR 
QUALITY OF THE CROP. 

The above are illustrations of the kind of mixtures which, on 

* It is prepared by pouring mixed solutions of sulphate of magnesia and 
sulphate of ammonia into a solution of the common phosphate of soda of 
the shops. 

\ See the Author's Experimental Chemistry^ p. 216. Also the Annales 
de Chemie for September 1852, p. 46. 



246 MIXTURES PROMOTING GROWTH 

the faith of results obtained by actual trial, may be recom- 
mended to the practical man as likely to increase the quantity 
of the crop. But mixtures may, by the reflecting farmer, be 
applied for other purposes. 



1. As when he mixes together 



Nitrate of Soda, 3 cwt. 

Gypsum, . . . , , . 5 " }• 28 cwt. 
Wood ashes, 20 ' 



)wt. ) 



and applies this mixture at the rate of 5 or 6 cwt. an imperial 
acre as a cure for clover-sick land — as recommended by Mr. 
Prideaux. 

2. Or when two good effects on the growth are sought for 
at the same time by the simultaneous application of two sub- 
stances to the crop. Or when an evil effect, considered likely 
to follow from the use of one substance alone, is to be pre- 
vented or counteracted by the use of another substance along 
with it. 

Thus, nitrate of soda applied to corn crops gives increased 
luxuriance, and greatly promotes the growth of straw, while it 
also increases the size of tiie ear But this rapid growth makes 
wheat, in some localities, liable to mildew. It is apt also to 
give a feebleness to the straw, which makes the crop more 
liable to be laid by the wind and rains ; so that if stormy wea- 
ther come when harvest approaches, the corn may be seriously 
damaged. On the other hand, common salt, while it usually 
strengthens and brightens the straw, makes mildew more rare, 
and adds, besides, to the weight of the grain per bushel. By 
using the two substances together, therefore, the increased 
growth caused by the nitrate will be secured, and mildew pro- 
bably prevented ; while the common salt will give the straw 
strength to stand. With this view experiments have been made 
with such a mixture by various persons, with the best results. 
I quote only two results, obtained at Holkbam by Mr. Keary, 
from applications to his wheat crops in 1850 and 1851. 



AND PREVENTING MILDEW. 24 T 

Application Produce, 

per imperial acre. Grain. Straw. 

1850. No application, ... 37 busk 26 cwt. 

Nitrate of soda, 1 cwt. . . 40 . . 32 . . 

Nitrate of soda, 1 • • [ aq oa 

Comiiiou salt, 2 . . f ' 

In this case the addition of salt produced no increase above 
the nitrate alone, except in augmenting by 2 cwt. the weight of 
the straw. 



1851. No application, . . . SYi bush. 27 cwt 

Nitrate of soda, 1 cwt. . . 431 . . 37 . . 
Nitrate of soda, 1 . . [ 

Common salt, 2 . . J * 



45^ .. 36* 



In this experiment the grain was increased nearly 2 bushels 
by the salt, while the straw was lessened by 1 cwt. These 
differences are of little pecuniary consequence. The chief ad- 
vantage to be looked for from the use of the salt is, as I have 
said, in its making more sure the gain which nitrate of soda, on 
all poor soils, and especially upon sickly crops, may be expected 
to produce. 

SECTION VII. ^USE OF ARTIFICIAL MIXED MANURES, COMPOUNDED 

IN IMITATION OF NATURAL MANURES ARTIFICIAL GUANOS. 

The above experiments illustrate how saline mixtures may 
be made and used for a definite and known purpose, other than 
that of simply adding to the natural produce of the land. But 
mixtures may also be made, with the view of imitating nature, 
and of compounding by art those valuable manures which she 
furnishes in such variety, where we can do it effectually, and at 
a reasonable cost. 

Thus guano is a highly fertilising substance; and as the sup- 
ply brought to this country is limited, and the price at which it 
was sold, when first introduced into this country, was a great 

* Journal of the Rotjal Agricultural Society, vol. xiii. p. 210. See also 
for similar experiments by Mr. Pusey, vol. xii. p. 202. 



£0 19 0. 


[$4 Y5 


14 6 


3 63 


4 


1 00 


16 


37 


2 


50 


5 


1 25 


1 6 


38 



248 ARTIFICIAL GUANOS. 

bar to its extensive employment, I was induced at the time to 
recommend the following, or some similar mixture — as likely to 
resemble it in fertilising virtue, because it contains the same in- 
gredients, as determined by analysis — to be inexhaustible in 
supply, because prepared chiefly from the produce of our own 
manufactories — and to be at least as cheap as the best import- 
ed guano. 

315 lb. (7 bushels) of bone dust at 2s. 9d. a bushel, £0 19 0, 

100 " sulphate of ammonia, 

20 " of pearl ash, or 80 lb. of wood ashes, 

80 " of common salt, .... 

20 " of dry sulphate of soda, . 

25 " of nitrate of soda, .... 

50 " of crude sulphate of magnesia, . 

610 £2 7 6 $11 88 

This quantity should be equal in efficacy to 4 or 5 cwt. of 
guano, and may by many be made at a cheaper rate. 

This recipe has formed the basis of numerous varieties of ar- 
tificial guano which have been manufactured in different parts 
of the country, and sold under different names, and at various 
prices — some of them sufficiently low to indicate that either the 
mixtures are not good, or that they are not made of valuable 
materials. They have, therefore, been applied to the land with, 
as might be expected, very discordant results. 

Though we should never be able to manufacture an artificial 
guano equal to the native, this good effect to the practical man 
arose at once from the publication of the above recipe, and from 
the manufacture and sale of artificial guano — that natural guano 
fell remarkably in price, and with it rape-dust, bone-dust, and 
other costly manures of a similar kind. Thus chemistry pos- 
sesses an intelligible money value even to the working farmer. 

This question of cheapness is second only to that of eflQciency 
in a manure. To make these manures cheap is the next point 
after making them well. With many manufacturers — and un- 
fortunately with many purchasers too — cheapness is made the 



CHEAPNESS SECOND ONLY TO EFFICIENCY. 249 

first consideration; and hence mixtures are brought into the 
market at a low price, which are of comparatively little value, 
and can produce a sensibly profitable result in a few cases only, 
and upon peculiar soils. 

To make the manure cheap, the ingredients employed must 
be so. The refuse of manufactories has been looked to as a 
source of such cheap materials, and not without the prospect of 
ultimate advantage to the country. The use of such refuse, 
liowever, has, in the first instance, led to much imposition. The 
exact nature of the refuse must be known, and its uniformity 
and constancy of composition ascertained, before it can be safe- 
ly employed in the manufacture of any mixed manure. 

It is a great objection to the numerous artificial guanos and 
mixed manures now offered for sale, that the public have no 
guarantee, either of the competency of the parties who make 
them to devise a mixture which shall be universally advanta- 
geous — of their ability to select materials which shall render 
it of that uniform composition which is essential to its success 
— or of their good faith in endeavoring to secure such a compo- 
sition.* 

*For numerous recipes for particular crops, the reader is referred to the 
author's Lectures, 2d edition, p. 639-646. 



CHAPTER XIX. 

Use of lime in Agriculture. — Composition of limestones, chalks, corals, 
shell-sands, and marls. — Burning and slaking of lime, hydrate of lime, 
spontaneously slaked lime. — Effects of exposure to the air upon quick- 
lime. — Advantages of burning lime partly mechanical and partly chemi- 
cal. — Silicate of lime produced by burning. — Quantity of lime usually 
apphed to the land. — Visible improvements produced by Ume. — Why 
liming must be repeated. — How lime is gradually removed from the land. 
— Circumstances which modify the effects of lime upon the land. — Che- 
mical effects of caustic and of mild lime upon the soil. — What is meant 
by overliming. — Proportion of lime in overlimed land. — How overliming 
is to be remedied. — Exhausting effects of lime. — Is lime necessarily ex- 
hausting. 

The use of lime is of the greatest importance in practical 
agriculture. It has been employed in the forms of marl, shell, 
shell-sand, coral, chalk, limestone, limestone gravel, quick-lime, 
&c., in almost every country, and from the most remote period. 

SECTION I. COMPOSITION OF LIMESTONES AND CHALKS. 



When diluted muriatic acid, or strong 
vinegar, is poured upon pieces of lime- 
stone, chalk, common soda, or common 
pearl ash, effervescence takes place, and 
carbonic acid gas is given off, (p. 18.) 
If a current of this gas be made to pass 
through lime water, (see figure,) the 
liquid becomes milky, and a white pow- 
der falls, which is pure carbonate of lime. 
It consists of 




COMPOSITION OF LIMESTONES. 251 

Per cent 

Carbonic acid, 43-7 

Lime. 56-3 

100 
One ton of pure dry carbonate of lime contains, of 

Cwtau 

Carbonic acid, 8| 

Lime, Hi 

20 

Limestone and chalk consist, for the most part, of carbonate 
of lime. In soft chalk, the particles are held more loosely to- 
gether; in the hard chalks and in limestones, the minute grains 
have been pressed or otherwise brought more closely together, 
so as to form a more solid and compact mass. 

In regard to limestones and chalks, there are several circum- 
stances which it is of importance for the practical man to know. 
For example — 

a. That they are not composed entirely of mineral or inor- 
ganic particles, such as are formed by the passage of a current 
of carbonic acid through lime-water. They consist in great 
part, sometimes almost entirely, of minute microscopic shells, 
of the fragments of shells of larger size, or of solidified masses 
of corals, which formed coral reefs in ancient seas which once 
covered the surface where the limestones are now met with. 
The blue mountain limestones contain many of these coral reefs, 
while in our chalk rocks vast quantities of microscopic shells 
and fragments of shells appear. 

h. Being thus formed at the bottom of masses of moving wa- 
ter, the chalks and limestones are seldom free from a sensible 
admixture of sand and earthy matter. Hence, when they are 
treated with diluted acid, though the greater part dissolves 
and disappears, yet a variable proportion of earthy matter al- 
ways remains behind in an insoluble state. This earthy matter 



252 PHOSPHATE OF LDIE IX LIMESTONE. 

is sometimes less than half a per cent of the whole weight, 
though sometimes it amounts to as much as 30 or 40 per cent. 

c. Ail animals hitherto examined contain in the parts of their 
bodies traces more or less distinct of phosphoric acid, generally 
in combination with lime, forming phosphate of lime. This phos- 
phate of lime their remains, when dead, retain in whole or in 
part. It thus happens that limestones almost invariably con- 
tain phosphoric acid, and that the proportion of it usually in- 
creases with that of the visible remains of animals, shells, co- 
rals, &c., which occur in it. In the magnesian limestones of the 
county of Durham, I have found the proportion of phosphate of 
lime to be as small as 0.07 to 0.15 per cent ; while in a lime- 
stone from Lanarkshire (Carluke,) analysed in my laboratory, 
it amounted to IJ per cent ; or one hundred pounds of the 
burned lime contained as much as 21 pounds of phosphate of 
lime. 

d. The parts of animals also contain sulphur, and this has 
given rise to the presence of sulphuric acid in chalks and lime- 
stones. This acid exists in them in combination with lime — in 
the state of gypsum. The proportion of this gjq^sum which I 
have hitherto found in native chalks and limestones is small, 
varying from one-third to four-fifths of a per cent. 

e. Carbonate of magnesia, the common magnesia of the shops, 
is also present, almost invariably, in all our limestone and chalk 
rocks. In the purest it forms 1 or 2 per cent, in the most im- 
pure from 40 to 45 per cent of the whole weight. The rocks 
called dolomites or magnesian limestones, (p. 9t,) are charac- 
terised by the presence of a large proportion of carbonate of 
magnesia. In the old red sandstone formation also, beds of 
limestone occur which are rich in magnesia. Such limestones 
are usually considered less valuable for agricultural purposes. 
They can be applied less freely and abundantly to the land, and 
possess what practical men call a burning or a scorching quali- 
ty. They are, however, preferred to purer limes in some dis 



CORALS, SHELL SANDS, AND MARLS. 253 

tricts, as in the high lands of Galloway, for application to hill 
pastures. ^ 

SECTION II. COMPOSITION OF CORALS, SHELL-SANDS, AND MARLS. 

1°. Corah, as they are gathered fresh from the sea on the 
Irish (Bantry Bay) and other coasts, contain, besides carbonate 
of lime, a small percentage of phosphate of lime, and sometimes 
not less than 14 per cent of animal matter — (Jackson.) This 
animal matter adds considerably to the fertilising value of coral 
sand, when laid upon the land in a recent state, or when made 
into compost. 

2°. Shell-sand consists of the fragments of broken shells of 
various sizes, mixed with a variable proportion of sea sand. It 
contains less animal matter than the recent corals, and its value 
is diminshed by the admixture of sand, which varies from 20 to 
to per cent of the whole weight. On the shores of many of 
the Western Islands, shell-sand is found in large quantities, and 
is extensively and beneficially applied, especially to the hill-side 
pastures, and to peaty soils. 

3°. Marls consist of carbonate of lime — generally the frag- 
ments of shells — mixed with sand, clay or peat in various pro- 
portions. They contain from 5 to as much as 80 or 90 per cent 
of carbonate of lime, and are considered more or less rich and 
valuable for agricultural purposes as the proportion of lime in- 
creases. They are formed, for the most part, from accumula- 
tions of shells at the bottom of fresh-water lakes which have 
gradually been filled up by clay or sand, or by the growth of 
peat. 

SECTION III. OF THE BURNING AND SLAKING OF LIME. 

1°. Burning. — Limestones, when of a pure variety, consist 
almost entirely of carbonate of lime. This carbonate of lime, 
as we have seen, contains about 56 per cent of lime, or 11 J 
cwt. to the ton. 



254: BURNING AND SLAKING OF LIME. 

When this h'mestone is put into a kiln, with so much coal as, 
when set on fire, will raise it to a sufficiently high temperature, 
the carbonic acid is driven oif in the form of gas, leaving the 
pure lime behind. 

In this state it is known as burned lime, lime-shells, caustic 
lime, and quick lime, and possesses properties very different 
from those of the unburned limestone. It has a hot alkaline 
taste, absorbs water with great rapidity, falls to powder or 
slakes, and finally dissolves in t32 times its weight of cold water. 
This solution is known by the name of lime-water. 

2°. Slaking. — Its tendency to combine chemically with water 
is shown in the process of slaking. Almost every one is fami- 
liar with the fact that, when water is poured upon quick-lime, 
it heats, emits steam, swells, cracks, and at last falls to a fine, 
usually white, powder, which is two or three times as bulky as 
the lime in its unslaked state. When thus fully slaked and 
cool, the fine powder consists of — 

Lime, t6 per cent. 

Water, . ... 24 . 

100 

Or 20 cwt. of pure burned lime absorb and retain in the solid 
state 6J cwt. of water, forming 26J cwt. of slaked lime, called 
hydrate of lime by chemists. 

When quick-lime is left exposed to the air, even in dry 
weather, it gradually absorbs moisture from the atmosphere, 
and falls to powder without the artificial addition of water. 
In this case, however, it does not become sensibly hot as it does 
when it is slaked rapidly by immersion, or by pouring water 
upon it. 



SPONTANEOUS SLAKING. 255 



SECTION IV. OF THE CHANGES WHICH SLAKED LIME UNDERGOES 

BY EXPOSURE TO THE AIR, AND OF THE BENEFITS OF BURNING 
LIMESTONES. 

1°. Effects of ex'posure to the air. — When lime from the kiln 
is slaked by means, of water, it still retains its quick or caustic 
quality. But if, after it lias fallen to powder, it be left un- 
covered in the open air, it gradually absorbs carbonic acid from 
the atmosphere, gives off its water, and becomes reconverted 
into dry carbonate of lime. 

When lime is allowed to slake spontaneously in the air, it 
first absorbs water, and slakes, and falls to powder, and then 
absorbs carbonic acid and is changed into carbonate. 

But as soon as a portion of the lime slakes, it begins to absorb 
carbonic acid, probably long before the whole is slaked. Thus the 
two processes go on together, so that, in lime left to slake sponta- 
neously, as it is often on our fields and headlands, the powder 
into which it falls consists in part of caustic hydrate and in 
part of mild carbonate of lime. Its composition is nearly as 
follows: — 

Per cent. 
Carbonate of lime, 57.4 

Hydrate ofltae. \^^^,;,f,^^\ ■ . . 42.6 

100 

When it reaches this stage or composition, the remainder of 
the hydrate absorbs carbonic acid much more .slowly, so that 
when spread upon or mixed with the soil, it takes a much longer 
time to convert it into carbonate. At last, however, after a 
longer or shorter period of time, the whole of the lime becomes 
saturated with carbonic acid, and is brought back to the same 
state of mild ?<,?z-caustic carbonate in which it existed in the na- 
tive chalk or limestone before it was put into the kiln. 



256 ADVANTAGES OF BURNING. 

2°. Advantages of burning lime. — If the lime return to the 
same chemical state of carbonate in which it existed in the state 
of chalk or limestone, — what is the benefit of burning it ? 

The benefits are partly mechanical and partly chemical. 

a. We have seen that, on slaking, the burned lime falls to an 
exceedingly fine bulky powder. When it afterwards becomes 
converted into carbonate, it still retains this exceedingly mi- 
nute state of division ; and thus, whether as caustic hydrate or 
as mild carbonate, can be spread over a large surface, and be 
intimately mixed with the soil. No available mechanical means 
could be economically employed to reduce our limestones, or 
even our softer chalks, to a powder of equal fineness. 

b. By burning, the lime is brought into a caustic state, which 
it retains, as we have seen, for a longer or shorter jDcriod, till 
it again absorbs carbonic acid from the air or from the soil. 
In this caustic state, its action upon the soil and upon organic 
matter is more energetic than in the state of mild lime ; and 
thus it is fitted to produce effects which mere powdered lime- 
stone or chalk could not bring about at all, or to produce them 
more effectually, and in a shorter period of time. 

c. Limestones often contain sulphur in combination with iron, 
(iron pyrites.) The coal or peat, with which it is burned, also 
contains sulphur. During the burning, a portion of this sulphur 
unites with the lime to form gypsum, by this means adding to 
the proportion of this substance, which naturally exists in the 
limestone. 

d. Earthy and silicious matters are sometimes present in 
considerable quantity in our limestone rocks. When burned 
in the kiln, th« silica of this earthy matter unites with lime to 
form silicate of lime. This silicate of lime, being diffused through 
the burned and slaked lime, and afterwards spread, in a mi- 
nute state of division, through the soil, is in a condition in which 
it may yield silica to the growing plant. 

Thus the benefits of burning are, as I have said, partly me- 
chanical and partly chemical. They are mechanical, inasmuch 



QUANTITY OF LIME REQUIRED. 257 

as, by slaking, the burned lime can be reduced to a much finer 
and more bulky powder than the limestone could be by any me- 
chanical means ; and they are chemical, inasmuch as, by burn- 
ing, the lime is brought into a more active and caustic state, 
and is, at the same time, mixed with variable proportions of 
sulphate and of silicate of lime — which may render it more 
useful to the growing crops. 

SECTION V. QUANTITY OF LIME USUALLY APPLIED TO THE LAND. 

The quantity of quick-lime laid on at a single dressing, and the 
frequency with which it may be repeated, depend upon the 
kind of land, upon the depth of the soil, upon the quantity 
and kind of vegetable matter which the soil contains, and upon 
the species of culture to which it is subjected. If the land be 
wet, or badly drained, a larger application is necessary to pro- 
duce the same effect, and it must be more frequently repeated. 
But when the soil is thin, a smaller addition will thoroughly 
impregnate the whole, than where the plough usually descends 
to the depth of 8 or 10 inches. On old pasture lands, where 
the tender grasses live in 2 or 3 inches of soil only, a feeble 
dressing, more frequently repeated, appears to be the more rea- 
sonable practice ; though in reclaiming and in laying down 
land to grass, a heavy first liming is often indispensable. 

In arable culture, larger and less frequent doses are admissi- 
ble, both because the soil through which the roots penetrate 
must necessarily be deeper, and because the tendency to sink 
beyond the reach of the roots is generally counteracted by the 
frequent turning up of the earth by the plough. Where vege- 
table matter abounds, much lime may be usefully added ; and 
on stiff clay lands, after draining, its good effects are very re- 
markable. On light land, chiefly because there is neither moist- 
ure nor vegetable matter present in sufficient quantity; very 
large applications of lime are not so usual, and it is generally 
preferable to add it to such land in the state of compost only. 



268 WHY LIME MUST BE REPEATED. 

The largest doses, however, which are applied in practice, 
alter in a very immaterial degree the chemical composition of 
the soil. The best soils generally contain a natural proportion 
of lime, not fixed in quantity, yet scarcely ever wholly wanting. 
But an ordinary liming,' when well mixed up with a deep soil, 
will rarely amount to one per cent of its entire weight. It re- 
quires about 400 bushels (12 to 15 tons) of burned lime per acre 
to add one per cent of lime to a soil of twelve inches in depth. 
If only mixed to a depth of six inches, this quantity would add 
about two per cent to the soil. 

Though the form in which lime is applied, the dose laid on, and 
the interval between the doses varies, yet in Great Britain, at 
least in those places where lime can be obtained at a reasonable 
rate, the quantity applied amounts, on an average, to from *I to 
10 bushels a-year. 

SECTION VI. VISIBLE IMPROVEMENTS PRODUCED BY LIME, AND 

WHY LIMING MUST BE REPEATED. 

The most remarkable visible alterations produced by lime are 
— upon pastures, a greater fineness, sweetness, closeness, and 
nutritive character of the grasses — on arable lands, the im- 
provement in the texture and mellowness of stiff clays, the more 
productive crops, their better quality, and the earlier period at 
which they ripen, comp^fred with those grown upon soils to 
which no lime has ever been added. 

This influence of lime is well seen when limed is compared 
with unlimed land, or when soils, which are naturally rich in 
lime, are compared with such as contain but little. Barley 
grown on the former is of better malting quality. The turnips 
of well-limed land are more feeding for both cattle and sheep. 
And the hill pastures on limestone soils, like those of Derby- 
shire, continue longer green in autumn, and yield a greater year- 
ly return of milk and cheese, than the soils which are produced 
from sandstone rocks. 



CROPS AND RAINS CARRY AWAY LIME. 259 

But this superiority gradually diminishes year by year, iii land 
artificially limed, till it returns again nearly to its original con- 
dition. On analysing the soil when it has reached this state, the 
lime which had been added is found to be in a great measure 
gone. In this condition the land must either be limed again, 
or must be left to produce sickly and unremunerating crops. 

This removal of the lime arises from several causes. 

1. The. lime naturally sinks, — more slowly perhaps in arable 
than in pasture or meadow land, because the plough is continu- 
ally bringing it to the surface again. But even in arable land, 
it gets at last beyond the reach of the plough, so that either a 
new dose must be added to the upper soil, or a deeper plough- 
ing must bring it again to the surface. 

2. The crops carry away a portion of lime from the soil. — Thus 
the following crops, including grain and straw, or tops and 
bulbs, carry off respectively — 

Of lime. 

25 bushels, wheat, about . 13 lb. 

40 .... barley, . . l? " 

50 .... oats, . . 22 " 

20 tons of turnips, about . 118 " 

8 ... potatoes, . . 40 " 

2 ... red clover, , . 17 " 

2 ... rye grass, . . 30 " 

The above quantities are not constant, and much of the lime 
is no doubt returned to the land in the straw, the tops, and the 
manure ; yet still the land cannot fail to suffer a certain annual 
loss of lime from this cause. 

3. The rains wash out lime from the land. — The rain-water 
that descends upon the land holds in solution carbonic acid 
which it has absorbed from the air. But water charged with 
carbonic acid is capable of dissolving carbonate of lime ; and 
thus year after year the rains, as they sink to the drains, or 
run over the surface, slowly remove a portion of the lime which 
the soil contains. Acid substances are also formed naturally by 
the decay of vegetable matter in the land, by which another 



260 CHEMICAL EFFECTS OF LIME UPON THE SOIL. 

portion of the lime is rendered easily soluble in water, and 
therefore readily removable by every shower that falls. It is a 
necessary consequence of this action of the rains, that lime 
must be added more frequently, or in larger doses, where much 
rain falls than where the climate is comparatively dry. 

SECTION VII. CIRCUMSTANCES WHICH MODIFY THE EFFECTS OF 

LIME UPON THE SOIL. 

There are four circumstances of great practical importance 
in regard to the action of lime, which cannot be too carefully 
borne in mind. These are — 

1. That hme has little or no marked effect upon soils in which 
organic — that is animal or vegetable — matter is greatly de- 
ficient. 

2. That its apparent effect is inconsiderable during the first 
year after its application, compared with that which it produces 
in the second and third years. 

3. That its effect is most sensible when it is kept near the 
surface of the soil, and gradually becomes less as it sinks 
towards the subsoil. And, 

4. That under the influence of lime the organic matter of the 
soil disappears more rapidly than it otherwise would do, and 
that, as this organic matter becomes less in quantity, fresh ad- 
ditions of lime produce a less sensible effect. 

SECTION VIII. CHEMICAL EFFECTS OF CAUSTIC LIME UPON THE 

SOIL. 

The chemical effects of lime upon the soil in the caustic and 
mild states are chiefly the following : — 

a. When laid upon the land in the caustic state, the first ac- 
tion of lime is to combine immediately with every portion of free 
acid matter it may contain, and thus to sweeten the soil. 
Some of the compounds it thus forms being soluble in water, 
enter into the roots and feed the plant, or are washed out by 



CHEMICAL EFFECTS OF CAUSTIC LIME. 261 

the springs and rains ; while other compounds which are insol- 
uble remain more permanently in the soil. 

l. Another portion decomposes certain saline compounds 
of iron, manganese, and alumina which naturally form them- 
selves in the soil, and thus renders them unhurtful to vegetation. 
A similar action is exerted upon some of the compounds of 
potash, soda, and ammonia — if any such are present — by which 
these substances are set at liberty, and placed within the reach 
of the plant. 

c. Its presence in the caustic state further disposes the organ- 
ic matter of the soil to undergo more rapid decomposition — it 
being observed that, where Ume is present in readiness to com- 
bine with the substances produced during the decay of organic 
matter, this decay, if other circumstances be favourable, will 
proceed with much greater rapidity. The reader will not fail to 
recollect that, during the decomposition of organic substances 
in the soil, many compounds are formed which are of importance 
ill promoting vegetation. 

d. It is known that a portion at least of the nitrogen which 
naturally exists in the decaying vegetable matter of the soil is 
in a state in which it is very sparingly soluble, and therefore 
becomes directly available to plants with extreme slowness. 
But when heated with slaked lime in our laboratories, such 
compounds readily give off their nitrogen in the form of ammo- 
nia. It is not unlikely, therefore, that hot lime produces a 
similar change in the soil, though more slowly — hastening, as 
above stated, the general decomposition of the whole organic 
matter, but specially separating the nitrogen, and causing or en- 
abling it to assume the form, first of ammonia, and afterwards 
of nitric acid, both of which compounds the roots of plants can 
readily absorb. 

e. Further, quick-lime has the advantage of being soluble to a 
considerable extent in cold water, forming lime-water. Thus 
the complete diffusion of lime through the soil is aided by the 
power of water to carry it in solution in every direction. 



26^ CHEMICAL EFFECTS OF MILD LIME. 



SECTION IX. CHEMICAL EFFECTS OF MILD LIME WHEN APPLIED TO 

THE SOIL. 

When it has absorbed carbonic acid, and become reconverted 
into carbonate, the original caustic lime has no chemical virtue 
over chalk or crushed limestone, rich shell-sand, or marl. It 
has, however, the important mechanical advantage of being in 
the form of a far finer powder than any to which we can reduce 
the limestone by art — in consequence of which it can be more 
uniformly diffused through the soil, and placed within the reach 
of every root, and of almost every particle of vegetable matter 
that is undergoing decay. I shall mention only three of the 
important purposes which, in this state of carhonate, lime serves 
upon the land. 

a. It directly affords food to the plant, which, as we have 
seen, languishes where lime is not attainable. It serves also to 
convey other food to the roots in a state in which it can be 
made available to vegetable growth. 

h. It neutralises (removes the sourness) of all acid substances 
as they are formed in the soil, and thus keeps the land in a 
condition to nourish the tenderest plants. This is one of the 
important agencies of shell-sand, when laid on undrained grass 
or boggy lands ; and this effect it produces in common with 
wood ashes and many similar substances. 

c. During the decay of organic matter in the soil, it aids and 
promotes the slow natural production of nitric acid. With this 
acid it combines and forms nitrate of lime — a substance very sol- 
uble in water — entering readily, therefore, into the roots of 
plants, and producing effects upon their growth which are very 
similar to those oflhe now well-known 7zz7r«^e of soda. The success 
of frequent ploughings, harrowings, hoeings and other modes of 
stirring the land, is partly owing to the facilities which these 
operations afford for the production of this and other natural 
nitrates. 



OYER-LIMED SOILS. 



263 



SECTION X. WHAT IS MEANT BY OVER-LIMING ? PROPORTION OF 

LIME IN OVER-LIMED LAND. HOW OVER-LIMING IS TO BE REM- 
EDIED. 

It is known that the frequent addition of lime, even to com- 
paratively stiff soils long kept in arable culture, will at length 
so open them that the wheat crop becomes uncertain, and is 
especially liable' to be thrown out in winter. 

To lighter soils, again, and especially to such as are reclaim- 
ed from a state of heath, and contain much vegetable matter, 
the addition of a large dose of lime opens and loosens them, 
often to such a degree that they sound hollow, and sink under 
the foot. This effect is usually ascribed to an over-dose of lime, 
and the land is commonly said to be over-limed. In this state it 
refuses to grow oats and clover, though turnips and barley 
thrive well upon it. 

Being desirous of ascertaining the proportion of lime re- 
ally present in land which has been brought by lime into such a 
condition, I obtained from Sir George Macpherson Grant a 
number of soils from different fields upon his estate of Ballin- 
dalloch, and caused them to be analysed in my laboratory. The 
results of the analyses were as follows : — 





a 


^ 


■^^ 


-a 


-S^ 




o . 




ni G . 


% 1 '^-< 


S Cr4 




c 




Ph a — 




Ph ei^ 




S'i^ 


sig 


>.-:z ® 


tJ-'i 




Organic matter, 


r^ 


03 


|1" 


Suth( 
Par 
soil 
sub 




10.29 


9.54 


5.65 


5.73 


5.23 


Salts soluble in water, 


0.45 


0.15 


0.50 


0.15 


0.44 


Oxide of iron, 


2.49 


3.68 


0.50 


0.96 


2.04 


Alumina, .... 


1.71 


2.54 


1.11 


1.48 


1.15 


Carbonate of lime, . 


1.40 


0.69 


1.10 


0.98 


0.67 


Oxide of manganese, 


trace. 


0.72 


trace. 


trace. 


0.22 


Carbonate of magnesia, . 


do. 


trace. 


do. 


do. 


trace. 


Insoluble matter, chiefly sand, , 


81.7t 


82.79 


91.20 


90.34 


89.60 


98.11 


100.11 


100.06 


99.64 


99.35 



264 HOW TO TREAT SUCH SOILS. 

In all these soils the quantity of carbonate of lime was 
much less than is usually found in fertile soils. I inferred, 
therefore, that the effects ascribed to the lime were not due to 
its presence in too large a proportion, compared with other 
soils. 

Two other facts aided me in arriving at a correct conclusion 
upon the subject. 

1. That these same soils were known to produce good oats 
when they had been some years in pasture, or when turnips 
had been eaten off them with sheep, and the ground thus 
trodden and consolidated by their feet. 

2. -That oats and clover prefer a stiffer, stronger soil in 
which to fix their roots, while turnips and barley delight in a 
light and open soil. 

It was therefore the mechanical, and not the chemical con- 
dition of the soils, wiiich caused the failure of the turnip and 
clover crops. Consolidate them by any means,* and these 
crops would become more certain. The remedies, therefore, 
were — 

a. To eat off the turnips always with sheep ; — or 

h. To consolidate the loose and open soil by the use of a 
heavy roller, a clod-crusher or peg-roller, or other similar me- 
chanical means; — or 

c. To use the cultivator as much as possible instead of the 
plough, and thus to avoid the artificial loosening of the soil 
which is caused by frequent ploughing. 

Still the questions were unsolved, — In what way does the 
lime produce, or aid the plough in producing, this opening of 
the soil ? — and how are these effects to be prevented in fu- 
ture ? 

I offer the following considerations, as affording a conjectu- 
ral explanation of this matter : — 

1. The lime, in whatever state it is added to the land, as- 
sumes in a short time the state of carbonate. 

2. In soils which are rich in decaying vegetables much acid 



EXHAUSTING EFFECTS OF LIME. 265 

matter is gradually produced by the action of the air. The 
acids thus produced decompose the carbonate of lime, and libe- 
rate its carbonic acid more or less copiously. 

3. The effect of this liberation of the carbonic acid gas may 
be to heave up the land, to loosen it and lighten it under the 
foot. In heavy lands this may be less perceived, both because 
they are naturally denser and more difficult to heave up, and 
because they contain less vegetable matter, and consequently 
produce less of these acid substances in the soil. In light 
peaty or thin moorish soils, however, which are rich in decay- 
ing plants, the particles of soil are more readily lifted up and 
separated from one another. 

Will this supposed action never cease ? It is doubtful if it 
will, until the nature of the soil is altered — by the gradual re- 
moval of the lime — by a diminution of the quantity, and a 
change in the nature of the decaying vegetable matter — or by 
a permanent solidifying of the land. 

This last change maybe effected either by a top-dressing of clay, 
sand, limestone-gravel, or other heavy matter, or by bringing up 
a heavier subsoil from below. Where the temporary solidifica- 
tion produced by eating off with sheep and the use of a roller is 
not approved of, the improvement of over-limed land is to be 
sought for in draining, subsoiling so as to admit the air into the 
under-soil, and, after a time, in bringing up and mixing with the 
surface a sufficient portion of this under-soil. 

SECTION XI. EXHAUSTING EFFECTS OF LIME. IS LIME NECESSARILY 

EXHAUSTING ? 

The exhausting effects of lime have been remarked from the 
earliest times. It causes larger crops to grow for a certain 
number of years, after which the produce diminishes, till at length 
it becomes less than before lime was applied to it. Hence the 
origin of the proverb that " Lime enriches the fathers and im- 
poverishes the sons." 
12 



266 ORGANIC MATTER DIMINISHES IN THE SOIL. 

Two interesting questions, therefore, suggest tliemselves in 
connection witli this circumstance. How is this exhaustion pro- 
duced ? Is it a necessary consequence of the addition of lime, 
or can it be prevented ? 

It has already been stated that lime promotes those chemical 
changes of the organic part of the soil by which it is rendered 
more serviceable to the growth of plants. But in consequence 
of this action, the proportion of organic matter in the soil grad- 
ually diminishes under the prolonged action of lime, and thus 
the soil becomes less rich in those substances of organic origin 
on which its fertility in some degree depends. 

Again, lime acts also on the mineral matter of the soil, and 
prepares it for more abundantly feeding the plant. 

Now, as the crops we reap carry off not only organic but min- 
eral matter also from the soil, anything which prepares that 
mineral matter more abundantly for the use of the plant must 
cause also a more rapid diminution of those mineral substances 
on which, as well as upon its organic matter, the fruitfulness of 
the soil is dependent. 

By this mode of action, therefore, arises the exhaustion which 
universal experience has ascribed to the use of lime. 

But without reference to the chemical processes by which it 
is brought about, a common-sense view of the question sufficient- 
ly explains how the exhaustion arises. 

It is conceded that the crops we grow rob the soil both of 
organic and inorganic matter. A double crop will take twice 
as much, a triple crop three times as much, and so on. And the 
more we take out in one year, the more rapidly will the land be 
exhausted. Now, if lime, by its mode of action, enables us in 
the same time to extract three or four times as much matter 
from the soil in the form of increased crops, it must so much 
the more rapidly exhaust the soil, in the same way as we 
should drain a well sooner by taking out fifty than by remov- 
ing only five gallons a-day. 

But we can restore to the soil what crops carry off. By 



THE SOIL CAN BE RESTORED feY MANURE, &C. 20*1 

farmyard manure, and by saline applications, we can return 
everything which the lime enables us thus to extract, and we 
can thus preserve its fertility unimpaired. Manure, therefore, 
in proportion to the crops taken off, and lime, will cease to be 
exhausting. There is much wisdom in the rhyme, 

"Lime and lime loWiout manivre 
.Will make both land and farmer poor." 



CHAPTER XX. 

Improvement of the soil by paring and burning. — Use and properties of 
burned earth and burned clay as improvers. — Effects of buriJing upon 
clay. — Smother-burning and over-burning. — How they improve the soil. 
— Improvement by means of irrigation. — Irrigation a kind of manuring. — 
How waters manure the land. — Composition of the water of the Hamp- 
stead water-works. — Different virtues of natural streams. 

There remain still a few important modes of improving the 
soil by forms of mineral and organic manuring, which it is ne- 
cessary briefly to notice. 

SECTION I. IMPROVEMENT OF THE SOIL BY PARING AND BURNING. 

A mode of improvement often resorted to on poor lands 
is the paring and burning of the surface. The effect of this 
treatment is easily understood. The matted sods consist of 
a mixture of much vegetable with a comparatively small 
quantity of earthy matter. When these are burned, the ash 
only of the plants is left, intimately mixed with the calcined 
earth. To strew this mixture over the soil is much the same as 
to dress it with peat or wood ashes, the beneficial effects of 
which are almost universally recognised. And the beneficial 
influence of the ash itself is chiefly due to the ready supply of 
inorganic food it yields to the seed, and to the effect which the 
potash and soda, &c., which it contains exercise either in prepar- 
ing organic food in the soil, or in assisting its assimilation in the 
interior of the plant. 

Another part of this process is, that the roots of the weeds 
and poorer grasses are materially injured by the paring, and 
that the subsequent dressing of ashes is unfavorable to their 
further growth. 



BURNED EARTH AND CLAY. 269 

It is besides alleged, and I believe with truth, that poor old 
grass land, when ploughed up, is sometimes so full of insects 
that the success of any corn or green crop put into it becomes 
very doubtful. When pared, these insects collect in the sod, 
and are destroyed by the subsequent burning. 

Paring and burning is a quick method of bringing land into 
tillage, and will secure one or two good crops. But it is 
exhausting, and the prudent man will rarely have recourse 
to it for the purpose of reclaiming land which is to be kept in 
constant tillage. It is very much less practised now than it 
was twenty or thirty years ago. 

Another evil also follows the practice of paring and burning. 
Where the land has little fall for drainage — is raised, that is, 
only a few feet above the level of the nearest brook — this 
paring and burning gradually lowers the level, and makes it 
impossible at last to drain it. In Northamptonshire I have 
been told of pieces of land, a few years ago two feet above 
the water level, which are now brought down to that level by 
the repetition of this hurtful practice. This is certainly enriching 
the farmers and impoverishing the sons. 

SECTION II. ON THE USE AND PROPERTIES OF BURNED EARTH 

AND CLAY AS IMPROVERS. 

1^, Burned earth and clay have long been recognised by the 
farmer as useful applications, in certain circumstances, to his 
land. Mixed with much vegetable matter of any kind, and 
burned slowly and without free access of air, stiff soils of all 
sorts will give blackened heaps, which may be spread with ad- 
vantage as a top-dressing, or employed, as in China, to cover the 
seed after it has been committed to the earth. 

To the light porosity of the earth, and to the action of the 
vegetable ashes which are mixed with it, the beneficial influence 
of such burned mixtures is distinctly to be ascribed. 

2°. Burned day^ in which little organic matter exists, and 



2*10 CAUSE OF THEIR USEFUL ACTION. 

with which little is mixed during the burning, must owe any 
fertilising properties it possesses to a different cause. Such 
clay, properly prepared, has in numerous instances been found 
beneficial when applied to the land. It is usually laid on in 
large doses, and acts both mechanically and chemically. 

a. Mechanically, in rendering the soil more friable, so that it 
can be worked with less labor, and in esjDCcially aiding the cul- 
ture of green crops. 

I. Chemically, in considerably increasing the produce. Thus 
Mr. Pusey found a dressing of burned Oxford clay to increase 
his wheat crop from 3*1 J to 45 J bushels per imperial acre. 
And Mr. Danger, who farms on the new red sandstone, near 
Bridge water, says, that a soil which he found '* quite sterile, 
has, by the application of burned clay, become totally 
changed."* 

It is equally true, however, that burned clay has often failed 
to do any good — that the practice of burning clay, which is 
common in some districts, is for this reason never adopted in 
others — and that clay from the same locality may or may not 
do good according to the method of burning. 

All this is easily explained when the true cause of the 
chemical action of burned clay is understood. 

3°. Cause of its useful chemical action. — All clays contain 
sensible quantities of most of the mineral substances — potash, 
soda, lime, magnesia, phosphoric acid, &c. — which plants re- 
quire for their healthy growth. They are, however, in a com- 
paratively insoluble condition, which circum.stance, united to 
the stiffness of the clay, prevents the roots of plants from 
readily taking them up. When the clays are burned by a gen- 
tle heat, however, the chemical condition of the constituents of 
the clay is altered, and the substances which plants require are 
rendered more soluble. After the burning, both water and 
acids will dissolve out more from the same weight of dry clay, 

* Boyal Agricultural Journal, vi. 411, and xii. 509. 



OVER-BURNED CLAY. 211 

and the matter thus dissolved contains a large proportion of 
those mineral ingredients which all plants contain. In one ex- 
periment, I found that a ton of clay which, in the natural 
state, gave to water only 11 lb. of mineral matter, yielded 
readily 36 lb. after being burned. Besides, the clay is rendered 
more porous by the burning, so that water and the roots of 
plants can penetrate more easily to take up the soluble matter. 

Again, of burned clay, 50 to 100 tons an acre is not an un- 
usual application. Now, at 36 lb. to the ton, the largest dose 
would yield to water not less than 3600* lb. of soluble mine- 
ral matter ; while the whole quantity of such matter carried off 
in a four years' rotation, from our best farms, (p. 69,) is only 
1300 lb. It is not surprising, therefore, knowing, as we do, 
how applications of saline matter increase the crops, that so 
great and ready a supply of such matter in the burned clay 
should produce a marked effect upon the fertility of the laud 
upon which it is spread. 

But, further, all clays have not the same composition. Some 
contain more lime, others more magnesia, others more potash or 
fioda, and others more phosphoric acid ; while some, again, con- 
tain so little of any of these substances as to produce no sensible 
effect when burned and laid upon the land. Thus the chemical 
composition of a clay determines whether or not it can be burned 
and applied to advantage. 

Those clays ar6 likely to suit well which contain most alkaline 
matter, (potash and soda ;) next those which contain a cousid- 
erablij percentage of lime or magnesia, or phosphoric acid ; and, 
best of all, those which with the alkaline contain also the cal- 
careous matter. Hence it is that to clays which contain little 
lime it is a judicious recommendation that a quantity of slaked 
lime should be sprinkled upon the clay during its preparation for 
burning. 

In the fourth place, it is remarkable that, by too complete 
and prolonged a Imrning, the clay is again rendered less solu- 

* Expei'imentaL AgricuUiore, p. 261. 



212 IMPROVEMENT OF 

ble in water and in acids than before. Hence tlie evil of over- 
hurning, as it is called, and the reason why the same clay pre- 
pared in different ways does not produce the same good effects. 
The method of slow smothcr-hmmn^ — the heat being kept low, 
and free access of air prevented — is that which gives the most 
constant good results. 

Lastly, I notice, as a beneficial consequence of burning, that 
the burned clay, being generally porous, absorbs ammoniacal 
and other vapors from the air and from the soil more readily 
and abundantly than before, and fixes them for the use of plants. 
In the black smother-burned clay, which contains much iron, 
this metal, in absorbing oxygen from the air, may even give 
rise to the formation of ammonia, and thus, in another chemical 
manner, act favorably upon the soil. 

Advantage is taken of this porous quality of burned clay by 
some English farmers — as by Mr. Randall, of Chadbury, near 
Evesham — to absorb and preserve the droppings of sheep. 
Under house-fed sheep, kept upon boards or otherwise, a layer 
of burned clay is spread, upon which the droppings fall : from 
time to time fresh layers are added to the surface, till it be- 
comes necessary to remove the whole. In this way, the smell 
of the dung never becomes excessive, and the clay is rendered so 
rich that 10 tons of it are found equal, in the raising of turnips, 
to 4 cwt. of guano. 

SECTION III.- -ON THE IMPROVEMENT OF THE LAND BY IRRIGATION. 

The irrigation of the land is, in general, only a more refined 
method of manuring it. The nature of the process itself, how- 
ever, is different in different countries, as are also the kind and 
degree of eifect it produces, and the theory by Vvdiich these 
effects are to be explained, 

1. In dry and arid climates, where rain rarely falls, the soil 
may contain all the elements of fertility, and require only water 
to call them into operation. In such cases — as in the irriga- 



THE LAND BY IRRIGATION. 2t3 

tions practised so extensively in Eastern countries, and without 
which whole provinces in Africa and Southern America would 
lie waste — it is unnecessary to suppose any other virtue in 
irrigation than the mere supply of water it affords to the parch- 
ed and cracking soil. 

But in climates such as our own, there are several other be- 
neficial purposes in reference to the soil, which irrigation may, 
and some of which, ajt least, it always does serve — thus, 

2. The occasional flow oi jpure water over the surface, as in 
our irrigated meadows, and its descent into the drains, where 
the drainage is perfect, washes out acid and other noxious sub- 
stances naturally generated in the soil, and thus purifies and 
sweetens it. The beneficial effect of such washing will be rea- 
dily understood in the case of peat-lands laid down to water- 
meadow, since, as every one knows, peaty soils abound in 
matters unfavorable to general vegetation. These substances 
are usually in part drawn off by drainage, and in part destroy- 
ed by lime and by exposure to the air, before boggy lands can 
be brought into profitable cultivation. 

3. But it seldom happens that perfectly |?i<,re water is employ- 
ed for the purposes of irrigation. The waters of rivers, as they 
are diverted from their course for this purpose, are more or less 
loaded with mud and other fine particles of matter, which are 
either gradually filtered from them as they pass over and through 
the soil, or, in the case of floods, subside naturally when the 
waters come to rest. Or, in less frequent cases, the drainings of 
towns and the water from common sewers, or from the little 
streams enriched by them, are turned with benefit upon the fa- 
voured fields. These are evidently cases of gradual and uniform 
manuring. 

4. Even where the water employed is clear and apparently 
undisturbed by mud, it almost always contains ammonia, nitric 
acid, and other organic and saline substances grateful to the 
plant in its search for food, and which plants always contrive to 
extract, more or less copiously, as the water passes over their 

12* 



214 COMPOSITION OF THE HAMPSTEAD WATER. 

leaves or along their roots. The purest spring waters and 
mountain streams are never entirely free from impregnations of 
mineral and vegetable or animal matter. Every fresh access 
of water, therefore, affords the grass in reality another liquid 
manuring. 

5. In illustration of this, I insert the following analyses of the 
water supplied by the Hampstead Water-works, for the use of 
the city of London, as given by Mr. Mitchell. It contains in all 
40 grains of dry matter to the imperial gallon, which consists 
of— 



Carbonate of lime, 








3.83 gr 


ail 


Carbonate of magnesia, . 








3.41 


... 


Phosphate of hme. 








0.28 


... 


Sulphate of lime, 








4.42 


... 


Sulphate of potash, 








3.28 


... 


Sulphate of soda. 








4.81 




Chloride of sodimn (common 


salt,) 




17.76 


... 


Silica (soluble,) 




. 




0.28 


... 


Crenic acid, 




. 




0.17 


... 


Aprocrenic acid. 




, , 




0.08 


... 


Other organic matters, . 








1.72 




Oxides of iron and manganese, 






traces 


... 



40.04 

In this list of substances, we recognise nearly 'every mineral 
ingredient which is found in the ash of plants. But, in addition 
to these ingredients, nearly all river and spring waters contain 
appreciable quantities of ammonia and of nitric acid, which are 
not mentioned, and were probably not sought for by Mr. Mitchell. 
It is not surprising, therefore, that waters containing such sub- 
stances, in an available form, should promote vegetation when 
used for the purpose of irrigation. 

6. The kind of saline substances which spring water or that 
of brooks contains, depends upon. the nature of the rocks or soils 
from which it issues or over which it runs. In countries where 
granite or mica-slate abounds, potash and soda, and even mag- 
nesia, may be expected in notable quantities, while in limestone 
districts the waters are generally charged with lime. When 



WATERS DIFFER IX NATURAL VIRTUE. 2t5 

spread over the fields, these latter waters supply lime to the 
growing plants, and so affect the general fertility of the soil as 
to render almost unnecessary the direct application of lime 
to the land. The value of the mountain streams for the purpose 
of irrigation in limestone districts is so well known, that some 
have been inclined to undervalue all the constituents of natural 
waters, and to ascribe little worth as irrigators to the clear 
waters of brooks and springs which are not rich in lime. This 
opinion, however, is not in accordance with the-resultsof the an- 
alyses made in my laboratory, of waters which have been pro- 
fitably employed for irrigation. 

7. Flowing water also drinks in from the air, as it passes 
along, a portion of the oxygen and carbonic acid of which the 
atmosphere in part consists. These gaseous substances it 
brings in contact with the leaves at every moment, or it carries 
them down to the roots in a form in which they can be readily 
absorbed by the parts of the plant. It is not unlikely that, in 
consequence of this mode of action, even absolutely pure water 
would act beneficially if employed in irrigating the soil. 

8. Further, the constant presence of water keeps all the 
parts of the plant in a moist state, allows the pores of the 
leaves and stems to remain open, retards the formation of hard 
woody fibre, and thus enables the growing vegetable, in the 
same space of time, to extract a larger supply of food, espe- 
cially from the air. In other words, it promotes and enlarges 
its growth. 

In the refreshment continually afforded to the plant by a 
plentiful supply of water — in the removal of noxious substances 
from the soil — in the frequent additions of enriching food, 
saline, organic, or gaseous, to the land — in the soft and porous 
state in which it retains the parts of the plant, the efficiency 
of irrigation seems almost entirely to consist. 

9. To one other interesting point I must advert. It is 
known that waters which have passed over the surface of a 
field become sensibly less fertilising. This is easily explained, 



276 SPRING WATEK3 IN THE YOSGES. 

by tlie reasonable supposition that the plants among which 
they have flowed have deprived them of a portion of their en- 
riching matter. 

But, in the same neighborhood, it has been often observed 
that waters fropi natural springs which are perfectly alike in 
appearance, yet differ remarkably in their value for irrigation. 
Such is the case among the mountains of the Vosges, where ir- 
rigation is much attended to. The same quantity of water, 
from two neighboring springs, for example, employed on two 
adjoining meadows of similar quality, in 1848, gave of hay per 
acre — 





1st Cutting. 


2d Cutting. 


Total. 


Good spring, . 


58 cwt. 


24 cwt. 


82 cwt. 


Bad spring, 


14 .. 


H-. 


21^.. 



Or the good spring produced nearly four times as much hay as 
the bad one. 

A chemical examination of the waters of the two springs 
satisfied the experimenters (Chevandier and Salvetat) that this 
difference was not due, either, 

a. To the quantity or kind of the gases which the two waters 
held in solution ; nor 

h. To the quantity or kind of the mineral matters in which 
both were nearly equally rich ; nor 

c. To the quantity of organic matter, of which the bad 
water in reahty contained the most ; nor 

d. To the absolute quantity of nitrogen contained in this or- 
ganic matter — for the bad water actually spread the larger 
quantity over the soil ; but 

e. To the circumstance that the organic matter, though 
smaller in quantity, was richer in nitrogen. It contained six 
per cent of this constituent, while that of the poor water con- 
tained only two per cent. 

This result is in entire consistency with all I have stated on 
the subject of manures — of the necessity of nitrogen to the 
growth of plants (p. 51,; — of the tendency of such as are 



ENGLISH AND INDIAN RIVERS. 27 1 

rich in nitrogen especially to promote growth — and of the in- 
fluence of organic matters, rich in nitrogen, in enabling plants 
to work up the mineral and other ingredients in a mixed ma- 
nure*or in the soil, (p. 129,) which may happen to be within 
their reach.* 

* The following extracts in connection with waters good and lad for irri- 
gating, will interest .the reader: — 

" There are two brooks on this estate, Delamere, (the property of G. 
Wilbraham, Esq.,) — one a clear white water, the other brown — both of 
which abound in trout, and on each there are irrigated meadows. In the 
former stream the trout are large ; in the latter small, and never grow be- 
yond a certain size. The meadows watered by the former are green, lux- 
uriant, and productive ; those of the latter comparatively barren. It is 
supposed that the pernicious effects of the brown stream are occasioned by 
passing through peat or some mineral substance ; but the cause has never 
been satisfactorily demonstrated."' — Mr. Palin, " Ou the Agriculture of 
Cheshire," in Royal Agricultural Journal, of the Royal Agricultural Soci- 
ety, vol. V. p. 105. 

" On the property of the Earl of Caernarvon, near Exmoor, there are 
four streams : — the Hudson, containing excellent trout, and making su- 
perior water-meadows ; the Exe, inferior in the quality of the fish, and less 
beneficial to grass ; the Barle, worse again in each respect ; and lastly, the 
Danes' brook, containing no fish at all, and itself) as I am informed, poison- 
ous to grass land. The variation of their color confirms Mr. Paiin's opinion 
that these differences are owing to the presence of peat." — Ph. Pusey, 
ibid. Note. 

As a pendent to these home cases, I add the following regarding a. 
foreign river in different parts of its course : — 

" I ought to mention of the Tochee, that so long as it remains in Bunnoo, 
its waters are used both for irrigatioii and household purposes, and I never 
heard any complaint of it in either of these departments. But, changing 
its qualities with its name, in Merwiat, the Goombeeluh, as it is now called, 
is deemed useless for agriculture ; and though habit enables the natives to 
drink it with impunity, it is yexy injurious to strangers, producing, after a 
few days, and sometimes hours, great pain and inflammation." — A Year on 
the Punjab Frontier in 1848-49, by Major Herbert B. Edwards. Vol. i, 
p. 68. 



CHAPTER XXI. 

The products of vegetation. — Influence of different manures on the quan- 
tity of a corn crop. — Average composition of the grain of wheat, and 
influence of climate upon that composition. — Influence of manure on the 
proportion of gluten and yield of flour, — Experiments of Mr. Burnet. — 
Composition of the oat, and influence of variety on its composition and 
nutritive quality. — Composition of barley, and influence of circumstances 
on its sprouting, melting, and feeding properties. — Composition of rice, 
maize (Indian corn), and buckwheat. — Composition of the bean, the pea, 
and other leguminous seeds. — Composition of oily seeds, and nuts, and of 
the acorn. — Relation of the quality of the soil to the quality of our corn 
crops. 

The first object of the practical farmer is, to reap from his 
land the largest possible return of the most valuable crops, 
without permanently injuring or exhausting the soil. With, 
this view he adopts one or other of the methods of treatment 
above adverted to, by which either the physical condition or 
the chemical composition of the soil is altered for the better 

It may be useful to show how very much both the quantity 
and the quality of a crop is dependent upon the mode in which 
it is cultivated and reaped, and how much control, therefore, 
the skilful agriculturist really possesses over the ordinary pro- 
ductions of nature. 



SECTION I. OF THE INFLUENCE OF MANURE ON THE QUANTITY OF 

THE WHEAT AND OTHER CORN CROPS. 

Every one knows that some soils naturally produce much 
larger returns of wheat, oats, and barley than others do, and 
that the same soil will produce more or less according to the 
mode in which the land has been prepared — by manure or 



INFLUENCE OF MANURE. ■ 219 

otherwise — for the reception of the seed. The following table 
shows the effect produced upon the quantity of the crop by 
equal quantities of different manures applied to the same soil, 
sown with an equal quantity of the same seed : — 

Return in bushels from each bushel of seed. 



Manure applied. 


Wheat. 


Barley. 


Oats. 


Rye. 


Blood, . . 


14 


16 


121 


14 


Nightsoil, ■ . 


— 


13 


14^ 


13^ 


Sheep's dung, 


12 


• 16 


14 


13 


Horses' dung, 


10 


13 


14 


11 


Pigeons' dung, 


— 


10 


12 


9 


Cows' dung, 


7 


11 


16 


9 


Vegetable manure, . 


3 


7 


13 


6 


Without manure. 


— 


4 


5 


4 



It is probable that on different soils the returns obtained by the 
use of these several manures may not be uniformly in the same 
order, yet it will always be found that blood, nightsoil, and 
sheep, horse, and pigeons' dung, are among the most enriching 
manures that can be employed. (See table in pp. 213, 214.) 

It is a practical fact, bearing upon this point, that in some 
parts of Bedfordsliire, high-farming causes barley to run to straw, 
to the injury of the corn ; while, on the contrary, the wheat in- 
creases in yield with higher cultivation.* 

Two facts will particularly strike the practical man on look- 
ing at the above table. 

1. That exclusive of blood, sheep's dung, in these experiments, 
gave the greatest increase in the barley crop. The favorite 
Norfolk system of eating off turnips with sheep previous to 
barley, besides other benefits ^yhich are known to attend the 
practice, may possibly owe part of its acknowledged utility to 
this powerful action of sheep's dung upon the barley crop. Still, 
too much reliance is not to be placed on such special results till 
the experiments have been carefully repeated. 

2. The action of cows' dung upon oats is equally striking, and 
the large return of this crop (thirteen-fold) obtained by the use 

* Caird's EnglisJi Agriculture, p. 451. 



280 AVERAGE COMPOSITION OF THE GRAIN OF WHEAT. 

of vegetable manure alone, may perhaps explain why, in poorly 
farmed districts, oats should be a favorite and comparatively 
profitable crop, and why they may be cultivated with a certain 
degree of success on land to which rich manure is rarely added. 
It is possible, I repeat, that results different from those re- 
corded in the above table may be obtained by a careful repeti- 
tion of the same experiments on soils of different kinds and in 
different circumstances. It is very desirable, therefore, that such 
experiments should be undertaken, accurately conducted, and 
carefully recorded. 

SECTION II. AVERAGE COMPOSITION OF THE GRAIN OF WHEAT, 

AND INFLUENCE OF CLIMATE ON THAT COMPOSITION. 

The grain of wheat consists, on an average, of 



Water, 


14.0 


ratt}"- matter, .... 


1.2 


Protein compounds, 
Gluten and albumen, ) 


14. fi 


. it.o 


Starch and dextrin, 


66.9 


Cellular fibre, 


1.7 


Mineral matter, 


. • 1.6 



100 

This average composition does not truly represent the composi- 
tion of our British and European varieties of wheat. It makes 
the proportion of protein compounds rather too large. Climate 
and season are believed to influence the proportion of gluten, so 
that the grain of warm climates and hot seasons is generally 
richer in this ingredient. Thus four varieties gave to Peligot : — 



PECULIAR QUALITIES OF IMPORTED WHEAT, 281 

Flemish. French. Pohsh. Egyptian 









Grown, in France. 


Water, 


14.6 


14.6 


13.2 13.5 


Fat, . . 


1.0 


1.3 


1.5 1.1 


Protein compounds. 


10.7 


9.9 


21.5 20.6 


Starch, &c. 


11.9 


74.2 


61.9 64.8 


Cellulose, 


1.8 


? 


? ? 


Mineral Matter, 


? 


? 


1.9 ? 



100 100 100 100 

The increased proportion of protein compounds in the samples 
of Polish and Egyptian wheat is very remarkable ; and it is not 
less interesting that they had been grown in France from the 
foreign seed. This latter fact illustrates — what every practical 
farmer is familiar with- -that imported seed always retains for 
some seasons the peculiar qualities which distinguish it in the 
country from which it is brought. It is not to be supposed that 
all varieties of wheat from Poland or Egypt contain the large 
proportion of gluten found by Peligot in the above varieties, 
which must, I believe, be regarded as very rare and extreme 
cases. An increase of 2 or 3 per cent in the protein compounds 
is the most that can reasonably be expected in Eastern com- 
pared with British wheat ; and even this is by no means con- 
stant, as it is modified by season, by modes of culture, and by 
other causes. 

SECTION III. INFLUENCE OF THE KIND OF MANURE ON THE 

PROPORTION OF GLUTEN IN WHEAT, AND ON THE YIELD OF FLOUR. 

Among these other modifying causes may be mentioned the kind 
of manure by which its growth is assisted. That this is really ca- 
pable of altering the proportion of gluten contained in the grain 
is very probable ; though it has not as yet been experimentally 
established that it is capable of doing so in a very great degree. 
. Another influence of manure upon the grain of wheat appears 
less uncertain — that is, the proportion of fine flour which the 



per acre. 


from the grain. 


the flour. 


In bush. 


Per cent. 


Per cent. 


31i 


16 


9^ 


40 


66 


10^ 


49 


63 


9^ 


49 


65 


9^ 


48 


54 


10 



282 COMPOSITION OF THE OAT. 

grain will yield when sent to the mill. This is somewhat striking- 
ly illustrated by the following experiment : — 

The same variety of wheat, top-dressed with the same rich 
manure — suljphated urine, (jd. 201,) mixed with different saline, 
substances — and grown in the same season on the same fields, 
gave Mr. Burnett of Gadgirth — 

Manure. Produce Fine Flour Gluten iu 



No manure, .... 
Sulphated urine and -wood-ashes. 
Do. and sulphate of soda, . 
Do. and common salt, 
Do. and nitrate of soda, . 

In these results we see, first, that the produce of fine flour 
from the grain is very different in the different samples ; and 
second, that the rich top-dressings did not very largely increase 
the proportion of gluten in the flour. 

The whole produce of gluten in the crop was increased, be- 
cause the crop was increased in quantity ; but in none of the ex- 
periments was the percentage of gluten largely augmented. A 
flour peculiarly rich in gluten is required— such at least is the 
prevailing oj^inion — for the manufacture of macaroni and vermi- 
celli : and such is said to be the quality of the grain naturally 
produced in tiouthern Italy. Further experiments are required 
to show how far, by what means, and in what circumstances, the 
percentage of protein compounds can in this country be econo- 
mically increased by the management of the cultivator.* 

SECTION IV. COMPOSITION OF THE OAT, AND INFLUENCE OF VARI- 
ETY ON ITS COMPOSITION AND NUTRITIVE QUALITIES. 

The following analyses of two samples of Scotch oats, made 

* In the neighborhood of Kirkcaldy wheat is said to be poorer after early- 
lifted than after ripe potatoes. Is this the case ? — and if so, how is it to 
be explained ? 



COMPOSITION OF OATS. 



283 



in my laboratory by Professor Norton, will show the relative 
proportions iu which the several constituents exist in this kind 
of grain, and the amount of variation which these relative pro- 
portions are liable to undergo in this country in different vari- 
eties : — 

Composition of Oats, dried at 212 Fah.* 



Starch, 

Gum, 

Sugar, 

OD, 

Avenin,* 

Albumen,^ 

Grluten, 

Husk, 

Ash, 



Potato 


Hopetoun 


Oats. 


Oats. 


65.60 


64.80 


2.28 


2.41 


0.80 


2.58 


•7.38 


6.97 


16.29 


16.26 


2.17 


1.29 


1.45 


1.46 


2.28 


2.39 


2.60 


2.32 



100.85 



100.48 



The united percentage of the three varieties of 'protein compounds 
(within the bracket) in the oat" is very large ; and hence the 
very nutritive quality of this grain. But the quality of the oat, 
like that of wheat, varies with the soil, the climate, the manure, 
and the variety. As an instance of the latter, I may mention 
that the hinds in many parts of Scotland live only on oatmeal, 
of which they are allowed two pecks each a-week. If made from 
potato oats, the two pecks are often insufficient ; but when made 
from the common Angus oat, this quantity is frequently more 
than the hind can consume. 

SECTION V. INFLUENCE OF VARIETY ON THE QUANTITY OF PRODUCE, 

AND ON THE PROPORTION OF MEAL YIELDED BY THE OAT. 

The quantity, as well as the quality, of the grain of the oat 
yielded by the same soil is much affected by the variety of oat 
which is sown. The proportion of meal yielded by an equal 



* See page 47. 



284 



COMPOSITION OF BARLEY. 



weight of the grain is also materially aifected by the variety. 
This is shown by the following table of the results obtained by 
Mr. Hay from eight different varieties of oats well known in 
Scotland. The experiment was made in the year 1850, upon a 
thorough drained field of stiff cold clay with a relentive subsoil. 
All the varieties were sown on the 26th and 2tth of March, all 
reaped between the 20th and 26th August, and the extent of 
each experimental plot was three quarters of an imperial acre. 



Variety. 


Produce. 


Meal yielded 
by 100 lb. 
of grain. 


Grain. 


straw. 


Potato oat, .... 

Sheriflf 

Berlie 

Hopetoun 

Blainslie 

Sandy 

Early Angus 

Barbachla 

1 


bush. 
69 
651 
55^ 
56i 
52i 
47 
48i 
45 


cwt. 
621 
55^- 
55* 
56| 
601 
481 
451 
49 


lb. 
60^ 
52i 
58 
60^ 
5U 
. 60 
551 
601 



The differences in each of these three columns are very 
striking, and will suggest to the reader many interesting con- 
siderations, to which space does not permit me to advert. 

I only add, that in all the different grains we cultivate vari- 
ety is found to affect in a similar manner the quantities of pro- 
duce reaped. 

SECTION VI. OF THE AVERAGE COMPOSITION OF BARLEY. 

The Scotch oat is the most nutritious of our homegrown 
grains. Among the ancients, barley was highly esteem.ed for 
its feeding qualities The Greeks, Egyptians, and Hebrews 
made much use of it, and the wrestlers and gladiators ate only 
barley bread ; hence they were called hordearii* It is still re- 
cognised in this country as possessed of great feeding power, 
* Pliny, Book xviii. 



MALTING QUALITIES OF BARLEY. 285 

though the higher price obtained for samples which malt well 
has thrown somewhat into the shade its purely nutritive qual- 
ities. 

The average composition of fine barley meal is nearly as 
follows : — 



Water, .... 


14 


Protein compounds, . 


14 


Starch, &c.. 


68 


Fatty matter. 


2 


Mineral matter, 


2 



100 

The above is exclusive of the bran separated by the miller, 
which forms from 10 to 18 per cent of the weight of the grain. 
It shows the flour to be very nutritious, containing 14 per cent 
of the protein or flesh-forming constituent, while fine wheaten 
flour rarely contains more than 10 per cent. 

SECTION VIII. INFLUENCE OF CIRCUMSTANCES ON THE SPROUTING, 

MALTING, AND FEEDING QUALITIES OF BARLEY. 

1°. Malting qualities. — The malting of barley is known to be 
affected by various circumstances. Unless the grain be dry, it 
does not sprout readily, and hence it is customary for maltsters 
to sweat their barley on the kiln before malting it. The grain 
should also be so uniform in ripeness as to sprout uniformly, so 
that no part of it may be beginning to shoot when the rest has 
already germinated sufficiently for the maltster's purpose. On 
this perfect and uniform sprouting of the whole depends in some 
degree the swelling of the malt, which is of considerable conse- 
quence to the manufacturer. 

The uniformity of sprouting depends sometimes on the mode 
of husbandry practised where it is grown. Thus when barley is 
taken after turnips, if the land be merely cross-ploughed, the ma- 
nure which had been laid in the turnip drills will remain in lines 
along the field where the turnips had grown, and the barley along 



286 FEEDING QUALITIES OF BARLEY. 

those lines will ripen first. But if the land be ploughed diago'iv- 
ally, the manure will be equally spread and the barley nourished 
and ripened equally, and thus it will be likely to sprout uniform- 
ly also. 

But the malting quality of the grain, which is of more con- 
sequence to the brewer and distiller, is understood to be modi- 
fied chiefly by the proportion of gluten which the barley contains. 
That which contains the least gluten, and, therefore, the most 
starch, is supposed to malt the most easily and the most completely 
and to yield the strongest beer or spirit from the same quantity 
of grain. Hence the preference given by the brewer to the malt 
of particular districts, even where the sample appears otherwise 
inferior. Thus the brewers on the sea-coast of the county of 
Durham will not purchase the barley of their own neighbor- 
hood, if Norfolk grain can be had at a moderate increase of price. 
But that which refuses to malt well in* the hands of the brewer, 
will cause pigs and other stock to thrive well in the hands of the 
feeder, and this is the chief outlet for the barley which the brew- 
er and distiller reject, 

2°. Feeding qualities. — So far as a practical deduction can be 
drawn from the experiments hitherto made in regard to the 
effects of different manures upon the proportion of gluten in 
barley, it would appear that the larger the quantity of cows' 
dung contained in the manure applied to barley land — in otlier 
words, the greater the number of stock folded about the farmyard, 
the more likely is the barley to be such as will bring a high price 
fro7n the brewer. 

The folding of sheejp appears to produce a larger return from 
the barley crop, and the folding of cattle to give grain of a better 
quality. These points also, however, require to be elucidated 
by more careful experiment. Such statements stand in our 
books at present rather as guesses at the truth, than as deduc- 
tions from rigorously made observations. 



COMPOSITION OF BEAN, PEA, &C. 



287 



SECTION VIII. COMPOSITION OF RYE, RICE, MAIZE (^INDIAN CORN}, 

AND BUCKWHEAT. 

These four species of grain contain respectively, when dried at 
212° Fahr., of— 



Starch, &c., 

Protein compounds, . . 
Fatty matter, .... 

Husk, ) 

Mineral matter, . . ) 


Rye. 


Rice. 


Maize. | Buckwheat. 

1 


78.0 

12.5 

3.5 

6.0 


87.4 
7.5 
0.8 
3.4 
0.9 


71.6 

12.3 

9.0 

5.9 

1.2 


60.6 
10.7 

0.4 
26.0 

2.3 


100 


100 


100 


100 



These numbers, it will be understood, are liable to variation in 
different samples ; especially the quantity of protein compounds 
in rye varies, and that of the fatty matter or oil contained in 
Indian corn. In some varieties of the latter grain this oil is 
only 2 to 3, in others as much as 9, per cent of the dry cone. 

In their natural undried state they alt contain 14 to 15 per 
cent of water. It will be seen that, in so far as that the protein 
or muscle-forming ingredients are concerned, rice is the least, 
and rye and maize the most nutritious of these four varieties of 
grain. 

SECTION IX. COMPOSITION OF THE BEAN, THE PEA, AND OTHER 

LEGUMINOUS SEEDS. 



The bean, pea, lentil, vetch, &c., are distinguished from white 
corn by the large proportion of protein compounds they contain, 
and their consequently greater nutritive power.* They resemble 
each other very much in composition ; and in the state of dry- 
ness in which they are generally brought to market, as field 
crops, they consist of about 



288 COMPOSITION OF OILY SEEDS AND NUTS. 



Water, . . * . 


14 


Starch and sugar, 


48 


Protein compounds, (legumin,) 


24 


Fatty matter, 


2 


Husk, ' . . . . 


10 


Mineral matter . . . . 


2 



100 

The proportion of husk varies ; the pea, which contains 10 per 
cent, having generally a thinner, and the bean a thicker skin. 
The proportion of protein compounds varies from 20 to as high 
as 30 per cent ; and according to experiment, the kind of ma- 
nure employed materially influences this proportion. Manures 
rich in nitrogen cause it to increase. It is also an interesting 
fact that the young legumes, when just beginning to form in the 
shell, are exeedingly rich in protein compounds. The very 
young pea, for example, contains as much as 48 per cent ; while, 
as the above table shows, the ripe pea rarely contains more 
than 24 per cent (p. 51.) 

The kind of protein compound which exists in these grains 
possesses peculiar chemical properties, and has been called le- 
gumin, (p. 47 ;) but its nutritive quahties are believed to be 
very much the same as those of gluten and albumen. 

SECTION X. COMPOSITION OF THE OILY SEEDS AND NUTS, AND 

OF THE ACORN. 

Many seeds, like those of flax and rape, contain a much larger 
quantity of oil than the kinds of corn which are usually em- 
ployed as food for man. The same is the case with nuts. From 
the kernels of the walnut, for example, and from those of the sweet 
almond, upwards of half their weight of oil can often be extracted. 

1. Linseed and linseed cake. — Linseed contains from 20 to 30 
per cent of oil. -A large proportion of this is squeezed out in 
the oil mills, and sold under the name of linseed oil. The cake 
or residue which remains, still contains a considerable proportion 
of oir; and, as it is very nutritive, is extensively employed in 



COMPOSITION OF THE ACORN. 



the feeding of cattle. The relative values of the seed and the 
cake for feeding purposes, and the value of both compared with 
other kinds of food, is shown very nearly by the following 
table : — 







Composition of 




Linseed. Linseed cake. 


"Water, .... 


9 


10 


Protein compounds, . 


19 


22 


Starch, &c., 


34 


39 


OU, ... 


25 


12 


Husk, 


8 


9 


Saline mineral matter, 


5 


8 



100 100 

Both seed and cake, therefore, are very nutritious ; and even 
the pressed cake still contains more fatty matter than Indian 
corn, some varieties of which contain as much as 9 per cent. 

What is called starch in the above analyses is, in reality, a 
kind of mucilage or gum, which dissolves readily in water, but 
serves the same purposes as starch in the feeding of animals. 

2. Rape cakt is about of equal nutritive value with linseed 
cake, but is often refused by cattle on account of its hot and 
acrid taste : this repugnance, however, may be overcome by 
mixing the crushed cake with a small quantity of molasses, or, 
by boiling it into a jelly with one-third of bean-meal, and making 
this into a mess with cut straw or hay. Sheep eat it readily 
when fed upon cabbage, and if kept upon other green food they 
soon become accustomed to it, if copiously supplied with water. 
The lower market price of rape cake makes a knowledge of 
these circumstances of money value to the practical feeder. 

3. Nuts resemble the oily seeds in their composition ; and 
hence nut-cakes approach linseed cake in value as a food for 
cattle. 

4. The acorn is also very nutritious, though it does not con- 
tain much fatty matter. As it falls ripe from the tree it consists 
of— 

13 



290 INFLUENCE OF THE SOIL ON OUR CORN CROPS 



Water, .... 


32 


Protein compounds, 


15 


Starch and sugar, 


47 


Fatty matter, 


3 


Cellular iibre, 


2 


Mineral matter, . 


1 



100 

Were the acorn made as dry as the bean is usually sold, 
it would, weight for weight, be nearly as nutritive. Hence the 
fattening of pigs when turned into oak forests, the use of the 
common acorn in periods of famine in many countries, and the 
constant u^e of the sweet acorn, (that of the Quercus gramuntia 
of Linnaeus,) in parts of Spain and Sardinia, as a common food 
of the people. A sweet acorn is also regularly found in the 
North African markets of Constantine, Bona, and Algiers. 

The acorn is remarkable for containing as much as 1 per cent 
of sugar, of which a small portion is sugar of milk. Could the 
bitter astringent substance, which gives our common acorns their 
unpleasant taste, be readily extracted, it might become an ac- 
ceptable article of food in every country. 

SECTION XI. INFLUENCE OF THE CONDITION AND QUALITY OF THE 

SOIL ON THE QUALITY OF OUR CORN CROPS. 

We have already shown that the quantity of the crop is ma- 
terially affected by the character of the soil, but the quality of 
the x^roduce is no less affected by the same cause. Thus — 

1. Barley. — The varying quality of this grain raised in different 
localities is familiar to every farmer. On stiff clays, barley may 
yield a greater produce, (North Hampshire,) but it is of a 
coarser quaUty. On light chalky soils it is thin-skinned, rich in 
color, and, though light in weight, well adapted for malting; 
while on loamy lands and on sandy marls it assumes a greater 
plumpness, yet still retains its malting quality.* 

* See p. 95, on the growth of the Ware malt 



PECULIARITIES OF THE PEA AND BEAN. 291 

2. T^lieat. — Similar differences affect the same variet}^ of wheat 
when grown upon different soils. In a previous section it was 
stated that the quantity of gluten contained in wheat is believed 
to vary with the climate, and in some degree also with the ma- 
nure applied to the land ; but a similar variation occurs on unlike 
soils, when manured, or otherwise treated in every respect alike. 
The miller knows by experience the relative qualities of the wheat 
grown on the several farms in the neighborhood of his mill, so 
that even when his eye can detect no difference of quality be- 
tween two samples, a knowledge of the places where they were 
grown enables him to decide which of the two it will be most for 
his interest to buy. 

3. The oaf varies in quality likewise with the soil on which 
it is grown. The meal made from oats grown upon clay land is 
the best in quality, is the thriftiest, keeps the longest, and gen- 
erally brings the highest price. 

I lately visited a farm in Forfarshire, part of which consisted 
of a sharp gravelly soil on a slope, and part of flat boggy land, 
resting on marl. Oats were usually grown on both soils, and I 
asked what difference the tenant observed in the quality of the 
grain he obtained from each. " In appearance," he answered, 
" there is no difference ; I could take the samples to market, and 
get the same price for each. If I wanted them for seed, I would 
buy either of them indifferently at the same price ; but for meal 
for my own eating, I would give two shillings a boll more for 
the oats of the sharp land. The sharp land meal," he added, 
" gives a dry knotty brose and a short oat cake ; that from the bog 
land may do for porridge, but it makes bad soft brose and a tough 
cake." 

4. Rye also flourishes upon light and sandy soils in general, 
but when grown upon sandy marls it is found (in Germany) to 
yield much brandy. 

5. The pea and the bean are distinguished by similar peculiarities, 
when grown in light and in heavy soils. There are certain spots 
in the neighborhood of all large towns, which are known to 



292 BOILING AND PIG PEAS. 

produce tlie best boiling peas, — such as boil soft and mealy. 
Thus the gravelly slope of Hopwas Hill, near Tamworth, on the 
Lichfield road, grows the best sidder or boiling green peas for 
the Birmingham market ; the Yale of Tamworth in general 
growing only jpig peas — hard boilers used only for feeding. Lime 
and gypsum are said by some to impart the boiling quality, while 
by others exactly the reverse is stated. No doubt the different 
results are owing to differences in the soils upon which the seve- 
ral experiments were made. 

It is a remarkable circumstance, that on the London corn 
exchange, the dealers seldom buy British peas without first 
sending a sample to be boiled, — while foreign peas are gene- 
rally bought without any trial. They are almost invariably 
boilers. For split peas, used in making soups and pease-meal, 
it is obvious that this boiling quality is of great importance. 

The explanation of all these differences is, to a certain extent, 
simple. The relative proportions of gluten and starch in all 
vegetable juices, and seeds, is variable. The plant is fitted to 
flourish, to live in a comparatively healthy manner, and to per- 
form all its natural functions, although the supply of those 
kinds of food out of which its gluten is formed be greater or 
less within certain limits ; but the boiling, feeding, malting, or 
distilling quaUties of its stems, seeds, or roots will be materially 
affected by variations in this supply. 

Again, the proportion of gluten seems to be dependent upon 
the quality of the soil, not only because the nitrogen it con- 
tains is chiefly imbibed by the roots of the plant, but because 
this gluten is always associated with a certain small quantity 
of sulphur, phosphorus, and earthy matter, which can only be 
derived from the soil. Where these elements abound in the 
neighborhood of the roots, the plant may produce much glu- 
ten ; where they are absent, it may not ; so that the feeding 
and other important qualities of the plant depend no less upon 
the presence of sulphur and phosphorus in the soil, than UMcn 



CAUSE OF THESE DIFFERENCES. 293 

that of any of the so-called organic elements of which its se- 
veral parts are principally made up. 

Still it must be borne in mind, that these explanations of the 
differences observed on the corn exchange, and by the miller, 
are as yet hypothetical. The causes stated may produce the 
effects actually observed, but it has not been proved, by ana- 
lytical and other experiments, that they really do produce them. 
Mere age induces changes in the qualities of grain, such as I 
have described, which the miller values and is willing to pay for. 



CHAPTER XXII. 

Average composition of the potato, turnip, mangold- wurtzel, and carrot. — 
Influence of soil, variety, manure, &c., on the quality of the potato and 
the quantity of starch it contains. — Influence of soil, season, variety, and 
manure on the composition and feeding properties of the turnip. — Com- 
position of the cabbage, cauliflower, mushroom, turnip-top, and of hay, 
straw, and the leaves of trees. — Composition of fruits, and the effect of soil 
upon their quality and flavor. — Relative quantities of starch and gluten 
contained in our usually cultivated crops. — Quantity of oil or fat in grain, 
root, and hay crops. — Absolute quantity of food yielded by an acre of 
land under different crops. 

SECTION I. AVERAGE COMPOSITION OF THE POTATO, TURNIP, MAN- 

GOLD-WURTZEL, AND CARROT. 

1. The turnip tribe differs from the potato in two principal 
points. 

a. In the quantity of water they respectively contain. In 
the potato this forms three-fourths, but in the turnip nine-tenths, 
of the whole weight, when taken from the ground : or they 
consist of — 

Potato. Turnip. 
Water, .... 75 91 

Dry nutritive matter, . .25 -9 

100 100 

h. In the presence of starch in the potato, while the turnip 
contains in its stead a substance — pectose or pectic ^cid — whic^ 
contains more oxygen than starch, but serves the same pur- 
poses in the nutrition of animals, (p. 44.) 

2. The dry nutritive matter of the potato and turnip con- 
tains, on an average, about — 



IMPORTANCE OF THE POTATO. 295 





Potato. 


Turnip. 


Starch or pectose, 


62 


15 


Sugar and gum, 


15 


56 


Protein compounds, 


9 


15 


Fatty matter, 


1 


2 


CeUular fibre, 


9 


7 


Mineral matter, 


4 


5 



100 100 

This table shows also that the turnip contains more sugar 
than the potato, and is richer also in protein compounds. Hence 
the advantage derived from, and the preference generally given 
to it, in the feeding of stock. 

3. The dry matter of the mangold-wurtzel and the carrot 
resembles in composition that of the turnip. Some varieties of 
these roots contain still more sugar. They likewise surpass the 
turnip in their per-centage of dry nutritive matter. This, in 
the three roots, is nearly as follows : — 

Turnip. Mangold. Carrot. 

Dry nutritive matter, 8 to 12 15 14 to 20 

"Water, . . 92 to 88 85 86 to 80 



100 100 100 

Hence the generally more nutritive quality of the two latter 
roots, weight for weight. 

SECTION II. INFLUENCE OF SOIL, VARIETY, DEGREE OF RIPENESS, 

KIND OF MANURE, AND OTHER CIRCUMSTANCES, ON THE QUALITY 
OF THE POTATO, AND THE QUAJ^TITY OF STARCH IT CONTAINS. 

The potato is a crop of so much importance in this country, 
that it may be interesting to introduce a few more detailed re- 
ijiarks in regard to the variations which the quality, and especi- 
ally the proportion of starch contained in it, has been found to 
undergo. 

1. Influence of soil. — It is familiarly known to the potato grow- 
er, that clay soils produce waxy, and sandy soils mealy potatoes. 



296 INFLUENCE OF VARIETY 

But the condition of the land also exercises a material in- 
fluence both upon their growth and quality. When, for example, 
potatoes are planted in rich newly broken-up land, they run up 
greatly to shaws or tops, produce generally few or small tubers, 
and of bad eating quality, because they seldom ripen before the 
frost sets in. Thus in one case it was remarked by Mr. Thompson, 
of Kirby Hall, York, that Hack kidneys planted on such a soil 
seemed quite to have changed their character. Instead of the 
fine mealiness for which they are usually remarkable, they bore 
much more resemblance to a piece of yellow soap. They, how^ 
ever, proved excellent seed, and in the wet summer of 1843 
showed no failures, and gave a capital crop. They were certain- 
ly not ripe, and to this circumstance Mr. Thompson ascribed their 
badness for eating and their goodness for seed. 

Again, it has been observed that the quantity of starch is 
larger in potatoes which are grown upon land long in arable 
culture than upon such as is newly brought into cultivation or 
broken up from grass. Thus Mr. Stirrat states, that from one 
peck of potatoes grown upon land near Paisley, which had been 
almost constantly under crop for the last thirty years, he obtain- 
ed t lb. of starch, while another peck grown on his bleach-green, 
newly broken up, gave him only 4 lb.* 

2. Influence of variety. — On the same soil, different varieties 
produce different proportions of starch. Thus, in 1842, Mr. Flem- 
ing, of Barochan, obtained from four varieties of potato grown 
on his farm, the following percentage of starch : — 

Connaught Cups, . . . 21 per cent. 

Irish blacks, . . . , 164 

White Dons, . . . . 13 ... 

Red Dons, .... 10| 

These differences in the per-centage of starch become very 
striking when we calculate the relative quantities per acre yielded 

* See the Author's Lectures on Agricultural Cliemistry and Geology, 2d 
edit. p. 901. 



EFFECT OF MANURES. 2ftt 

by these varieties. Thus under similar treatment they gave re- 
spectively — 

Produce per acre. 
Of potatoes. Of starch. 
Cups, . . . I'dk tons. 2.9 tons. 

Rod Dons, . . lU 1.5 

White Dous, . . 18^ 2.4 

So that the lightest crop gave the most starch. Though Jive ton 
an acre heavier, the crop of white Dons gave half a ton less starch 
than the Connaught Cups. 

3. Effect of manures. — I have already mentioned the alleged 
influence of sea-weed, (p. 169,) and of skin parings, (p. 162,) in 
making potatoes waxy. It is not so surprising, therefore, that 
the kind of manure employed should affect in a sensible degree 
the proportion of starch yielded by the potato. Thus Mr. Flem- 
ing found his potatoes, raised with different manures in 1843, to 
give the following per-centage of starch : — 

Per cent. 

1. Cups with dung alone, gave - 14.5 of starch. 
and guano, - 14*4 

2. White Dons with guano alone, - 9.0 
and dung, - 10.2 

3. Rough reds with guano alone, - 15.7 
and dung, - 17.1 

4. Perth reds with guano alone, - 15.3 
and dung - 15.5 

These experiments show, first, that in so far as the proportion 
of starch is concerned, either dung alone, or half guano and half 
dung, may be used with equal advantage. The experiment upon 
the Cups shows this. Second, that a mixture of dung and guano 
is in this respect better than guano alone.* All the other trials 

* This arises from the tendency of the potato to rush up to stalk when 
manured with guano alone, — the eftect of the guano being more or less 
exhausted before the plant reaches maturity, or has time to form its tubers. 
When mixed with dung, the latter carries on the growth which the former 
may have left unfinished. 
13* 



298 INFLUENCE OF SOIL. 

show this, — ^while they show further, also, how much the propor- 
tion of starch depends upon the variety of potato we grow. 

These varying proportions of starch are of much moment to 
the practical farmer at the present time, when potato failures 
are so common, — inasmuch as the certainty of the growth of the 
potato, when used as seed, appears to he the greater, the smaller the 
per-centage of starch. 

4. Effect of other circumstances. — I advert briefly to three 
other circumstances which affect the quantity of starch con- 
tained in the potato. 

a. The effect of keeping is to diminish the quantity of starch. 
Potatoes which in October yielded readily 17 per cent of starch, 
gave in the following April only 14| per cent. 

In connection with the keeping of the potato, it is a very 
interesting fact, that the epidermis or outer covering of the 
skin consists of a thin layer of cork, without visible pores, and 
through which v/ater passes with extreme slowness. Hence 
the potato can be kept for months at a temperature of 86° 
Fahrenheit, without losing more than three per cent of its 
Aveight. 

h. The effect of frost is also to lessen the starch. It acts chiefly 
upon the vascular and albuminous part, but it also converts a 
portion of the starch into sugar, hence the sweetish taste of 
frosted potatoes. 

c. The heel end of the potato contains more starch than the 
rose end, and both more than th^ central part. Thus, a variety 
of red potato which yielded 21 per cent of starch from the heel 
end, gave me only 16 J from the rose end, and 14 per cent 
from the central part. 

SECTION III. INFLUENCE OF SOIL, SEASON, VARIETY, AND MANURE, 

ON THE COMPOSITION AND FEEDING PROPERTIES OF THE TURNIP. 

1. Soil. — That the soil has an influence on the composition 
of the turnip crop, has long been believed by the practical man, 



IXFLUENCE OF MANURE. 299 

because of the difference in the taste and feeding properties of 
the same kinds of turnip grown on different fields and farms. 

The chemical nature of this difference has lately been inves- 
tigated by Dr. Anderson. Ilis analyses of turnips, grown in 
the same season and circumstances, upon 

a. The heavy alluvial clay of the Carse of Gowrie ; 

h. The black land which separates the clay from the hill, 
and there, as in- Lincolnshire, skirts the slopes ; 

c. The hill land, which is a light loam — 
showed that the proportion of nitrogen or of protein compounds 
was almost always greater on the hill laud than on either of 
the other soils — sometimes twice as great. The turnips of the 
black land were also slightly superior in this respect to those 
of the clay. This result of analyses fully supports that of prac- 
tical experience in the feeding of stock. 

2. Season. — The same analyses have confirmed another opin- 
ion of practical men, that the turnips of different seasons differ 
in their nutritive properties. Thus, in 1850, the turnips, from 
all the varieties of soil above mentioned, contained a smaller 
per-centage of protein compounds than in 1849, and the dif- 
ferences among them were less. The proportion of phosphates 
was also considerably less in the turnips of 1850. 

3. Variety. — The influence of variety is more striking, per- 
haps, on the turnip than upon any other of our more largely 
cultivated crops. The swede not only keeps better and longer, 
but is also sweeter and more nourishing than the white globe 
or yellow turnip. Hence in our large towns, when swedes, as 
they sometimes do, sell for 30s. a ton, the yellow will bring 
only 25s., and the globe turnip 18s. 

4. Manure. — The kind of manure afi'ects the quality and 
feeding properties of the turnip. According to the experiments 
of Mr. Lawes,* it appears that where a field is in a condition 
to produce an average crop of turnips, the proportion of ni- 

* Journal of the Royal Agricultural Society of England, viii. 494. 



300 COMPOSITION OF THE CABBAGE. 

trogen in the crop — that is of albumen and other protein com- 
pounds, which are very nutritive — may be increased by the ap- 
plication of animal or other manures containing iiitrogen — such 
as pigeons' dung, guano, woolen rags, rape cake, the salts of 
ammonia, nitrate of soda, &c. Mr. Lawes states, that by the 
use of such manures the proportion of this valuable ingredient, 
compared with what is contained in turnips raised by farm- 
yard manure, may be doubled. This result has, to a certain 
extent, been confirmed by the more recent analyses of Scotch 
turnips published by Dr. Anderson.* 

It is desirable, however, that the results of experiments in 
the laboratory, as to the composition of the crop, should be 
tested by after experiments with the same turnips in the actual 
feeding of cattle. Such experiments are difficult of execution, 
and require much care, but they are necessary to the attain- 
ment of results on which the practical man can be requested 
confidently to rely. 

SECTION IV. COMPOSITION OF THE CABBAGE, CAULIFLOWER, MUSH- 
ROOM, TURNIP-TOP, HAY, STRAW, AND THE LEAVES OF TREES. 

1. The Callage is one of the most nutritious crops we grow. 
Like the turnip, it contains a large proportion of water — about 
89 per cent ; but the dry matter of the cabbage is much more 
rich in protein or tissue-forming compounds than that of the 
turnip. It consists very nearly of — 

Starch, sugar, &c., 46 

Protein compounds, (albumen, &c.) . . 30 to 35 

Oil or fat, 3 

Cellular fibre, 9 

Saline or mineral matter, . . . . 12 to 18 

100 
The value of the cabbage in feeding — especially for milch 

* Quarterly Journal of Agriculture for January 1852, pp. 221-233. 



HAY, STRAW, AND LEAVES OF TREES. 301 

COWS — and its exhausting effect upon the soil, are not therefore 
to be wondered at. 

2. The Caulijlower is still more nutritious than the cabbage 
leaf. It contains about 64 per cent of protein compounds. In 
this respect it approaches nearer to animal food than any ve- 
getable we grow, of which the composition has yet been ex- 
amined. 

3. The Mushroom comes nearest to the cauliflower in this 
respect. It contains about 56 per cent of protein compounds ; 
and though by some found to be indigestible, its nutritive qua- 
lities are very generally admitted. 

4. The Turnip-top, though apt to scour cattle if given too 
freely, is generally as nutritive as the bulb. It contains as 
large a per-centage both of protein compounds and of phos- 
phates, especially when young. The young sprouts which tur- 
nips, left in the field, throw out in spring, resemble cabbage 
very much, and are very nutritious. Hence the reason why 
turnips which have thrown out large leaves in spring are gene- 
rally found less valuable in feeding. 

The composition of the turnip-top indicates the cause both of 
its great value as a manure when left upon the land, and why 
it forms a very appropriate food for the milch cow and the 
growing calf. 

5. Hay and Straio are distinguished by the large proportion 
of cellular or woody fibre, in an indigestible state, which they 
contain. Good hay, however, contains also from 6 to 9 per 
cent of protein compounds, and clover hay even as much as 12 
per cent ; so that, in muscle-forming matter, hay is nearly as 

-•rich as our English wheat. The straw of our white-corn plants 
contains only 3 or 4 per cent of these compounds. Pea and 
bean straw are more nutritious — good pea straw approaching 
in this respect to the best clover hay. 

6. The Leaves of Trees are often very nutritious ; and did 
they not frequently contain substances which render them un- 
palatable or unwholesome when eaten, they might be very ex- 



302 COMPOSITION OF FRUITS. 

tensively employed as food for cattle. The dry tea-leaf con- 
tains about 25 per cent of protein compounds, chiefly albumen, 
and would prove as nutritious in this respect as an equal weight 
of beans or peas, were it the fashion in Europe to eat it. The 
tobacco leaf contains about 23 per cent. The elephant — the 
largest of existing quadrupeds — lives much upon leaves in its 
native forests ; and in some Alpine countries, the annual har- 
vest of dried leaves forms an important part of the winter's 
provision for the domesticated cattle.* (See p. 316.) 

It is not surprising, therefore, that leaves should form a valu- 
able manure, or that poor land should be permanently improved 
by planting it with trees. (P. 158.) 

SECTION v. OF THE COMPOSITION OF FRUITS, AND THE EFFECT 

OF SOIL UPON THEIR QUALITY AND FLAVOR. 

To fruits it is necessary to do little more than allude in the 
present work.f They contain from tO to 90 per cent of water 
— the quantity diminishing as the fruit ripens. In the fleshy 
fruits — plums, peaches, &c. — when ripe, the water forms about 
*I5 per cent ; in apples, pears, and gooseberries, a little more 
than 80 per cent of the whole weight. The dry matter con- 
tains chiefly sugar and pectic acid, with a considerable propor- 
tion of protein compounds and of soluble phosphates. Fruits 
are therefore fitted to nourish as well as to refresh. The dried 
gooseberry contains about 9 per cent of protein compounds. 
The acidity of our usually cultivated fruits is due to the pre- 
sence of variable quantities of malic and citric acids. 

In cider, perry, and wine countries, the nutritive qualities of 

* " For several mileS, when crossing the high Alps of Savoy, we ob- 
served the peasants stripping the mountain ash trees of all their leaves, for 
their cattle during the winter." — Weld's Tour in Auvercjne and Piedmont. — 
[Were these leaves gathered for food or for litter ?] 

f For fuller information, see the Author's pubhshed Lectures. 



INFLUENCE OF TIME OF CUTTING. 303 

the apple, pear, and grape are seen in the use of the refuse of 
the mills in feeding pigs or other animals ; or where it is not 
used up in this way, these qualities are equally shown by the 
profitable employment of the refuse as a manure. 

Fruits of all kinds, like our corn and root crops, arc affected 
in flavor and quality by the soil on which they grow. In the 
Norman orchard, the gout de terrain is a recognised quality 
both in the apple and in the cider. The extended apple and 
peach culture of North America has led to similar observations ; 
and the peculiar qualities possessed by the wines of neighboring 
vineyards are familiar everywhere. There are only three farms 
situated on the side of a hill which produce the famous Con- 
stantia wine. The same grape has been tried in various parts 
of the Cape colony without success. Even a mile from the hill 
the wine is of a very inferior description. In Europe, on the 
banks of the Rhine, the Johannisberg is equally well known for 
the unique qualities of its celebrated wine. 

SECTION VI. INFLUENCE OF THE TIME OF CUTTING ON THE QUANTITY 

AND QUALITY OF THE PRODUCE OF HAY AND CORN. 

1. Hay. — The period at which hay is cut, or corn reaped, 
materially affects the quantity (by weight) and the quality of 
the produce. It is commonly known that when radishes are 
left too long in the ground they become hard and woody — that 
the soft turnipy stem of the young cabbage undergoes a similar 
change as the plant grows old — and that the artichoke becomes 
tough and uneatable if left too long uncut. The same natural 
change goes on in the grasses which are cut for hay. 

In the blades and stems of the young grasses there is much 
sugar and starch, which, as they grow up, are gradually 
changed into woody or cellular fibre, (p. 42.) The more com- 
pletely the latter change is effected — that is, the riper the 
stem of the plant becomes — the less sugar and starch, both 
readily soluble substances, its various parts contain. And 



304 CUTTING STRAW AND GRAIN. 

though it has been ascertained that cellular fibre is not wholly 
indigestible, but that the cow, for example, can appropriate a 
portion of it for food as it passes through her stomach — yet the 
reader will readily imagine that those parts of the food which 
dissolve most easily, are also likely, other things being equal, 
to be most nourishing to the animal. 

It is ascertained, also, that the weight of the hay or of the 
straw we reap, is actually less when it is allowed to become 
fully ripe ; and therefore, by cutting soon after the plant has 
attained its greatest height, a larger quantity, as well as a bet- 
ter quahty of hay, will be obtained, while che land also will be 
less exhausted. 

2. Straw. — The same remarks apply to crops of corn — both 
to the straw and to the grain they yield. The rawer the crop 
is cut, the heavier and more nourishing the straw. Within 
three weeks of being fully ripe, the straw begins to diminish in 
weight ; and the longer it remains uncut after that time, the 
lighter it becomes, and the less nourishing, 

3. Grain. — On the other hand, the ear, which is sweet and 
milky a month before it is ripe, gradually consolidates — the 
sugar changing into starch, and the milk thickening into the 
gluten and albumen of the flour. As soon as this change is 
nearly completed, or about a fortnight before it is ripe, the 
^rain of wheat contains the largest proportion of starch and 
gluten. If reaped at this time, the bushel will weigh most, 
and will yield the largest quantity of fine flour and the least 
bran. 

At this period the grain has a thin skin, and hence the small 
quantity of bran. But if the crop be still left uncut, the next 
natural step in the ripening process is, to cover the grain with 
a better protection — a thicker skin. A portion of the starch of 
the grain is changed into woody fibre — precisely as in the 
ripening of hay, of the soft shoots of the dog-rose, and of the 
roots of the common radish. By this change, therefore, the 
quantity of starch is lessened and the weight of husk increased j 



WHEN OATS SHOULD BE CUT. 305 

hence the diminished yield of flour, and the increased produce 
of bran. 

Theory and experience, therefore, indicate about a fortnight 
before it is fully ripe as the most proper time for cutting wheat. 
The skin is then thinner and whiter, the grain fuller, the bushel 
heavier, the yield of flour greater, its color fairer, and the 
quantity of bran less ; while, at the same time, the straw is 
heavier, and contains more soluble matter than when it is left 
uncut until it is considered to be fully ripe. 

In regard to oats, it is said that the superiority of Ayrshire 
oatmeal is partly owing to the grain being cut rather glazy, 
(that is, with a shade of green upon it,) and the straw is con- 
fessedly less nourishing for cattle when the crop is allowed 
to stand till it is dead ripe. Early cut oats, also, are heavier 
per bushel, fairer to the eye, and usually sell for more money. 
A week before full ripeness, however, is the utmost that is re- 
commended in the case of oats, the distance of the top and 
bottom grains upon the stalk preventing the whole from becom- 
ing so uniformly ripe as in the ear of wheat. 

Barley cut in the striped state is also thinner in the skin, 
sprouts quicker and more vigorously, and is therefore preferred 
by the maltsters. It is also fairer to the eye, and generally 
brings a higher price in the market. 



SECTION VII. OF THE RELATIVE QUANTITIES OF STARCH AND GLUTEN 

IN OUR USUALLY CULTIVATED CROPS. 

In addition to the details already given in regard to the 
composition of the several kinds of grain and roots usually cul- 
tivated in this country, it may be useful to exhibit, in a tabular 
form, the relative proportions of starch and gluten contained in 
each. The following numbers cannot be considered as precisely 
accurate, yet they represent pretty nearly the average quanti- 
ties of these two substances contained in 100 lb. of our common 



306 PROPORTIONS OF STARCH, GLUTEN, 

crops in the state of dryness, &c., in which they are usually 
sent to market : — 





Starch, gum, 


Gluten, albu- 




and sugar. 


men, &c. 


Wheat, (flour,) .... 


55 


10 to 19 


Bran of wheat, . . . 


— 


16 


Barley, 


60 


12 to 15 


Oats, (without husk,) 


60 


14 to 19 


Rye, 


60 


10 to 15 


Indian corn (maize,) 


•70 


12 


Bran of do 


— 


13 


Rice, 


1o 


1 


Beans, peas, vetches, and lentils, 


40 to 50 


24 to 28 


Linseed, 


40 


24 


Potatoes, 


18 


2 


Do. sliced and dried, 


72 


8 


Turnips, carrots, and mangold- wurtzel, 


9 to 11 


l^to 2 


Do. sliced and dried, . 


90 


12 to 16 


Cabbage, . . . , . 


— 


30 to 35 



These numbers are somewhat open to correction. Indeed, if 
the reader recollects what has been stated in the previous sec- 
tions, in regard to the variable quality of the different crops we 
raise, he will understand that the numbers contained in all 
tables such as this are to be regarded only as approximations 
to the truth. 



SECTION VIII. OF THE QUANTITY OF OIL OR FAT IN GRAIN, ROOT, 

AND HAY CROPS. 

It is generally known that linseed, rape-seed, turnip-seed, 
hemp-seed, poppy-seed, and the seeds of many other plants, 
abound so much in oil, that it can be squeezed out by strong 
pressure, as is done in the mills of the oil manufacturers. The 
kernels of some nuts also, as those of the walnut, the hazel, and 
the beech, contain much oil ; and even some trees, as certain 
species of the palm, yield it in large quantities. 

It has only recently been discovered, however, that all our 
cultivated grains contain an appreciable quantit}' of oil or fatty 



AND OIL IN DIFFERENT CROPS. 



307 



matter — that it is present also in our root crops, and that even 
in straw and hay it exists in sensible proportion. 

Soil, climate, mode of culture, manure, and the variety of 
the plant we grow, all affect the proportion of oil which its 
seeds, stems, or roots contain. To extract this oil we have 
only to reduce the part of the plant into minute fragments, to 
boil these in ether, filter the solution, and afterwards distil off 
the ether, when the oil or fat will remain behind. It is usually 
more or less of a yellow color, and when heated, not unfre- 
quently emits an odor peculiar to the plant. Thus the oil from 
the oat emits, when heated, the well-known odor of burned 
oatmeal. 

The proportion of oil contained in 100 lb. of some of our 
more commonly cultivated plants is as follows : — 



Wheat flour (fine), 




2 to 4 lb 


Bran of wheat, 




3 to 5 lb. 


Barley, 




2 to 3 lb. 


Oats, 




5 to 8 lb. 


Indian corn, 




5 to 9 lb 


Linseed, 




30 to 35 lb. 


Eape and turnip seeds, 




40 1b. 


Potatoes, turnips, and cabbage, . 


1-5 lb. 


Wheat straw. 


. 


2 to 3^ lb. 


Oat straw, 


. 


4 1b. 


Meadow hay, 


, 


2 to 5 lb 


Clover hay. 


. 


3 to 5 lb. 



The quantity of fat varies, as this table shows, in the same 
kind of food. These variations are caused by differences in 
the soil, manure, climate, season, &c. In most seeds, however, 
the largest proportion of fat resides in the exterior part, near 
to or actually in the husk or bran. Hence the bran of wheat 
generally contains much more oily matter than the fine flour. 
Thus in two varieties of wheat, the fine flour from which con- 
tained only li, the bran contained from 3 J to 5 per cent of fat. 

To this large quantity of oil, bran owes part of its value in 
feeding pigs, as we shall see more clearly when, in a subsequent 
chapter, we come to consider the important part which this 



308 FOOD YIELDED BY AN ACRE 

fatty matter performs in the artificial rearing and fattening of 
stock. 

SECTION IX. ON THE ABSOLUTE QUANTITY OF FOOD YIELDED BY AN 

ACRE OF LAND UNDER DIFFERENT CROPS. 

The quantity of food capable of yielding nourishment to 
man, which can be obtained from an acre of land of average 
quality, depends very much upon the kind of crop we raise. 

In the seeds of corn, when fully ripe, little sugar or gum is 
generally present ; and it is chiefly by the amount of starch 
and gluten* they contain, that their nutritive power is to be 
estimated. In bulbs, such as the turnip and potato, sugar and 
gum are almost always present in considerable quantity in the 
state in which these roots are consumed, and this is especially 
the case with the turnip. These substances, therefore, must be 
included among the nutritive ingredients of such kinds of 
food. 

If we suppose an acre of land to yield the following quan- 
tities of the usually cultivated crops, namely — 

Of wheat, 
Of barley, 
Of oats, ■ 
Of pease, 
Of beans. 
Of Indian corn. 
Of potatoes, 
Of turnips, 
Of wheat straw, 
Of meadow hay. 
Of clover hay, ■■ 
Of cabbage. 



25 bushels 


or 1,500 lb. 


35 .. 


or 1,800 . , 


50 


or 2,100 .. 


25 .. 


or 1,600.. 


25 


or 1,600 .. 


30 .. 


or 1,800 . . 


12 tons, 


or 27,000 .. 


30 .. 


or 67,000 .. 


u .. 


or 3,000 . . 


n .. 


or 3,400 . . 


2 .. 


or 4,500 .. 


20 


or 45,000 . . 



The weight of dry starch, sugar, and gum — of gluten, albumen, 
casein, &c. — of oil or fat — and of saline matter, reaped in each 

* Including under gluten the albumen, avenin, legumin, and casein — all 
the varieties of the protein compounds, in short, which arc contained in 
gram. (See page 47.) 



OF DIFFERENT CROPS. 309 

crop, will be represented very nearly by the following num- 
l)ers : — 





Husk or 


Starch, 


Gluten, al- 


Oil or 


Saline 




woody fibre. 


sugar, &;c. 


bumen, &c. 


fat. 


matter 


Wheat, 


225 


825 lb. 


180 lb. 


45 


30 


Barley, 


270 


1080 


230 


50 


50 


Oats, 


420 


1050 


300 


100 


•75 


Pease, 


130 


800 


380 


34 


48 


Beans, 


160 


640 


420 


40 


50 


Indian corn, 


100 


1260 


220 


130 


30 


Potatoes, 


1080 


4800 


540 


45 


240 


Turnips, 


1340 


6000 


1000 


200 


450 


Wheat straw, 


1500 


900 


40 


80 


150 


Meadow hay. 


1020 


1360 


240 


120 


220 


Clover hay. 


1120 


1800 


420 


200 


400 


Cabbage, 


430 


2300 


1300 


130 


600 



1. If it be granted that the quantities above stated are fair 
average returns of the different kinds of produce from the same 
quality of land — that the acre, for example, which, in our cli- 
mate, produces 25 bushels of wheat, or 30 of Indian corn, will 
also produce 50 bushels of oats, or 12 tons of potatoes, or 30 
of turnips, and so on * — then it appears that the land which, 
by cropping with wheat, would yield a given weight of starch, 
gum, and sugar, would, when cropped with barley or oats, 
yield one-fourth more of these substances — with potatoes about 
four times as much — and with turnips eight times the same 
quantity. In other words, the piece of ground which, when 
sown with wheat, will maintain one man, would support one 
and a quarter if sown with barley or oats, four with potatoes, 
and eight with turnips — in so far as the nutritive power of these 
crops depends upon the starch, sugar, and gum they contain. 

* These are not by any means to be regarded as universally equivalent 
crops. Even m our country, local climate modifies very much the relative 
quantities of the same crops obtained in difierent localities. Thus, in the 
southern part of Wigtonshire, 30 tons of Swedes, 20 tons of mangold, and 
20 tons of white carrots per acre are equivalent crops, while in Berkshire 
it is as easy to grow 30 tons of mangold as 20 tons of Swedes per acre. 
See Journal of the Royal Agricultural Society ^ vol. xiii. part i. 



310 



RELATIVE NUTRITIVE VALUES 



2. Again, if we compare the relative quantities of gluten, 
&c., in the several crops, we see that wheat, barley, and Indian 
corn yield, from the same breadth of land, nearly equal quan- 
tities of this kind of nourishment — oats one-half more, peas and 
beans upwards of twice, potatoes upwards of thrice, turnips 
upwards of four times, and cabbage six times as much as wheat or 
Indian corn. 

On whichever of these two substances, then — the starch or 
the gluten — we consider the nutritive property of the above 
kinds of food to depend, it appears that the turnip is, on the 
whole, the most nutritive crop we can raise. It is by no means 
the most nutritive, weight for weight; but the largeness of the 
crop — here taken at 30 tons — affords, us from the same field a 
much greater weight of food than can be reaped in the form 
of any of the other crops above mentioned. 

If, again, we look to th% gluten alone, none of our crops can 
compete with the cabbage, even supposing the crop not to ex- 
ceed 20 tons an acre. 

3. Further, the oil or fat they contain is not without its 
value in relation to the nutritive, and especially to the fattening 
properties of the different crops. In this respect also the tur- 
nip would appear to be superior to most of the other usual 
forms of vegetable produce. Clover hay and Indian corn can 
alone be compared with it. 

In these two facts the practical farmer will see the peculiar 
adaptation of the turnip husbandry to the rearing and fatten- 
ing of stock. Could the turnip be rendered an agreeable 
article of general human consumption, the produce of the land 
might be made to sustain a much larger population than under 
any of the other kinds of cropping above oJluded to. At- 
tempts have been made to grind them, and convert them into 
meal, as is done with the potato; but the cost of manufactur- 
ing, and the disagreeable taste of the meal, have hitherto stood 
in the way of a successful prosecution of this branch of rural 
industry. 



OF DIFFERENT VEGETABLE SUBSTANCES. 311 

The relative nourishing powers of different vegetable sub- 
stances, or their value for food, is supposed by some to depend 
entirely upon the relative proportions of gluten, &c., they con- 
tain. According to this view, the pea and the bean are much 
more nourishing, weight for weight, than wheat, or any other 
grain, since 100 lb. of beans would afford as much gluten to an 
animal as 230 lb. of wheaten flour or Indian corn, or as 130 lb. 
of oats or 200 lb. of rye ; and, in like manner, an acre of cab- 
bage would support both more people and more stock even 
than an acre of turnips. This opinion, however, is not alto- 
gether correct. 

But we shall be able to form a better judgment in regard to 
the relative value of the starch and gluten, as well as to under- 
stand the importance of the salim matter of the food, when we 
come in a succeeding chapter to consider the several purposes 
which the food is destined to serve in the animal economy — 
what different substances the animal must derive from its food 
in order to nourish its growing body, to maintain its existing 
condition when full grown, or to admit of a healthy Increase in 
its bulk. 



CHAPTER XXIII. 

Of milk and its products. — The properties and composition of mQk. — Influ- 
ence of breed, constitution, food, soil, &c., on its quantity and quality. — 
Adulteration of milk. — Composition of cream. — Churning. — Quality, 
composition, preservation, and coloring of butter. — Theory of the action 
of rennet. — Manufacture, quality, and varieties of cheese. 

Of, the indirect products of agriculture, milk, butter and 
cheese are among the most important. They are in reality ne- 
cessaries of life in all civilised countries, and are almost the sole 
productions of many agricultural districts. The various 
branches of dairy husbandry present also many interesting sub- 
jects of inquiry, on which modern chemistry throws much 
light. 

SECTION I. OF THE PROPERTIES AND COMPOSITION OF MILK. 

Milk is a white opaque liquid, possessed of a slight but pecu- 
liar odor. It is heavier than water, usuall}? in the proportion 
of 103 to 100. When left at rest for a number of hours it se- 
parates into two portions — the cream, which rises to the sur- 
face, and the thinner creamless milk on which it floats. When 
the whole milk or the cream alone is agitated in a churn, the 
fatty part of the milk separates in the form of butter, while 
the milk itself, butter-milk, becomes shghtly sour. 

If left to itself for several days, milk sours and curdles ; and 
if in this state it be placed upon a linen cloth, the liquid part, 
or whey, will pass through, while the curd or cheesy part will 
remain on the cloth. The same effect is produced more rapidly 
by adding vinegar to the milk, lemon juice, muriatic acid (spirit 
of salt), or rennet. In Holland the milk is sometimes curdled 



COMPOSITION OF MILK. 313 

for the manufacture of cheese by the addition of muriatic acid; 
but in most countries rennet is employed for this purpose. It 
is coagulated also by alcohol or any strong spirit, and hence, 
probably, the practice of adding a quantity of. whisky or 
brandy to the rennet — as is done in many dairy districts. 

When exposed to the air for a length of time, milks begins 
to putrefy and to ferment. It becomes disagreeable to the 
taste, emits an offensive smell, and ceases to be a wholesome 
article of food. 

The milk of nearly all animals contains the same ingredients 
— cheesy matter or casein, butter, milk-sugar, and saline mat- 
ter, but in different proportions. The best known varieties of 
milk consist nearly of 





Woman. 


Cow. 


Ass. 


Goat. 


Ewe. 


Casein, (or curd,) 


1.5 - 


4.5 • 


■ 1.8 


- 4.1 . 


• 4.5 


Butter, 


3.6 - 


3.1 ■ 


• 0.1 


- 3.3 • 


• 4.2 


Milk-sugar, 


6.5 - 


4.8 • 


■ 6.1 


- 5.3 • 


• 5.0 


Saline matter, 


0.5 - 


0.6 . 


. 0.3 


- 0.6 • 


0.7 


Water, 


87.9 - 


87.0 . 


• 91.7 


- 86.7 • 


. 85.6 



100 100 100 100 100 

The milk of the ass appears from the above table to resem- 
ble woman's milk, in containing little cheesy matter and much 
sugar. It contains also much less butter than any of the other 
varieties above mentioned, and hence, probably, its peculiar 
fitness for invalids. 



SECTION II. INFLUENCE OF BREED, CONSTITUTION, FOOD, SOIL, 

&C., ON THE QUANTITY AND QUALITY OF THE MILK. 

Both the quantity and the quality of the milk are affected 
by a great variety of circumstances. Every dairy farmer 
knows that his cows give more milk at one season of the year 
than at another, and that the quality of the milk also — its 
richness in butter or in cheese — depends, among other condi- 
tions, upon the kind of food with which his cows are fed. It 
14 



814 INFLUENCE OF CIRCUMSTANCES 

will be proper to advert to these circumstances a little in 
detail. 

1. The quantity and quality of the milk are affected by the 
breed. — Small breeds generally give less milk, but of a richer 
quality. Good ordinary cows in this country yield an average 
produce of from 8 to 12 quarts a-day. Thus the dairy cows of 

Devonshire give 12 quarts a-day, 
Lancashire - 8 to 9 quarts a-day, 



Cheshire and ) o ^ j 

Ayrshire, [ ^ ^"^^^^ ^ ^^^' 



19 


25 oz. 


17 .. 


28 oz. 


20 


34 oz. 



during ten months of the year ; but crossed breeds are, in 
many districts, found more productive of milk than the pure 
stock of any of the native races. 

The influence of breed ])oth on the quantity and on the qua- 
lity of the milk appears from the following comparative pro- 
duce of milk and butter of one cow of each of four different 
breeds, in the height of the season, and when fed on the same 
pasture. The 

Milk. Butter. 

Holderness gave 29 quarts and 883 oz. 
Alder ney^ 
Devon^ 
Ayrshire^ 

Not only was the quantity of milk very di^rent in the four 
cows, but the produce of butter also — the Holderness, in the 
quantity both of milk and of butter, being greatly superior to 
all the other breeds. 

The milk of the Holderness and of the Alderney breeds 
was equally rich in butter, as was the case also with that of the 
Devon and the Ayrshire, since 1 lb. of butter was yielded by 

12 quarts of milk from the Holderness cow, 
2 . . , . Alderney cow, 
9| . . . . Devon cow, 
9|- . . . . Ayrshire cow. 

Some stocks of Jersey cows produce 1 lb. of butter from 8 J 



ON THE QUANTITY AND QUALITY OF MILK. 315 

quarts of new milk, the year round, and at the same time con- 
sume less food than others. 

The butter of the milk is often in great part derived directly 
from the fat of the food. Hence the value of food which, like 
Indian corn and linseed cake, is rich in oil. Hence, also, those 
animals which lay the smallest proportion of this fat upon their 
own bodies will be likely to give the largest proportion in their 
milk. Thus the ■ Ayrshires and Alderneys, which are good 
milkers, are narrow across the shoulders, and wiry and muscu- 
lar about the flanks. They give a rich milk, but rarely fatten 
well. The short-horns, on the contrary, are celebrated for their 
fattening tendency. They deposit more of the fat under their 
skin, and impart less of it to their milk. In both breeds, how- 
ever, there are striking exceptions, because — 

2. The individual form and constitution of the coiv causes both 
the yield and the richness to vary much among animals of the 
same breed. Every dairy farmer knows that some Ayrshire, 
or Holderness, or Devon cows are better milkers than others. 
And even when they yield nearly the same quantity of milk, the 
richness or produce in butter may be very unlike. Thus, four 
cows of the Ayrshire breed, fed on the same pasture, gave in 
the same week — the 

Milk. Butter. 

First, ... 84 quarts which yielded 82 lb. 
Second and third, each, 86 . . . . 63 " 

Fourth, ... 88 .. . . 7 " 

SO that the fourth, though it produced only four quarts more 
milk, gave twice as much butter as the first. 

Individual cases of extraordinary productiveness occur now 
and then. Thus a Durham cow belonging to Mr. Hewer of 
Charleton, Northampton, gave in the height of the season 8 
imperial gallons of milk in a day, yielding 3 lb. of butter. A 
cow upon ordinary keep has been known also to produce as 
much as 350 lb. of butter in a year. The tendency to yield 



316 CONSTITUTION AND FOOD. 

butter is no doubt constitutional, like the tendency to lay on 
fat. 

3. The kind of food also exercises, as all cowfeeders know, 
much influence upon the quantity and upon the richness of the 
milk.* The Swedish turnip and the cabbage give a richer 
milk, the white globe turnip a larger quantity, while both vari- 
eties of turnips are said to cause a greater yield of milk when 
tops and bulbs are given together. Culpepper recommends the 
leaves of the black alder as a fodder for causing cattle to give 
much milk. (See p. 302.) Spurry is said to have a similar 
effect. When fed on grass and brewers' grains, the cow yields 
a larger quantity of milk; and when fed on malt dust, she 
drinks much and milks well. 

It is believed also, that cabbage and the leguminous plants, 
such as clover, tares, &c. — as well as the cultivated seeds of 
such plants, beans, peas, &c. — promote the production of 
cheese ; while oilcake, oats, Indian corn, and other kinds of 
food, which contain much oily matter, favor the yield of butter. 
The cakes left by oily seeds, linseed, poppy seed, dodder, sesa- 
min, give a milk which contains more solid matter, and is richer 
both in butter and cheese. If the cake be not old or rancid, it 
does not impair when given in moderate quantities, but rather 
increases the flavor and pleasantness of the butter. 

If the food contain little fat, the animal still produces butter 
It has the power of changing the starch and sugar of its food into 
fat during the process of digestion. It even robs its own body 
of fat, becomes leaner, and thus yields more fat in the form of 
butter than it has eaten in its food. Where only part of a 
dairy of cows is kept for tloeir butter, and the rest for cheese, 
the butter-milk from the former may be given to the latter, and 
thus the produce of cheese increased. In the State of New 
York, cows are said to yield 100 lb. more cheese in a year 

* Hence the Ayrshire adage, " The coio gives the milk by the inou.^^ 



INFLUENCE OF THE SOIL. 317 

when the whey from their own milk is added to their daily 
food. 

4. The nature of the soil also in which plants grow, and the 
manure by which they are raised, affects their influence upon 
the milk. It has been known from the most remote times, 
that when fed upon one pasture the cow will yield more butter, 
upon another more cheese. This difference must depend upon 
the soil. Again, it has been found by experiment, that vetches 
grown upon well-limed or marled land promote the production 
of cheese, while, after a manuring with wood-ashes, they in- 
crease the quantity of milk and of cream, (Sprengel.) In 
Cheshire the addition of bones has greatly increased the value 
of the grass, and the produce of milk and cheese ; while, as to 
the quality, it has been found in Leicester that the manuring of 
old pasture with good farm-yard manure, rendered the cheese 
for three years nearly unsaleable. 

On this curious subject numerous experimental researches are 
still required. 

5. The milk is affected also by a variety of other circum- 
stances. Its quantity depends very much upon the distance 
from the time of calving, diminishing as the calf in the womb 
gets older. This is no doubt a natural adaptation to the wants 
of the calf, which, in a state of nature, gradually ceases to re- 
quire support from its mother. A cow which, during the first 
fifty days after calving, yields 24 quarts of milk a-day, may 
yield no more than 6 quarts a-day after six months have 
elapsed. 

The quality of the milk is better from cows that are in good 
condition and have already been two or three times in calf — it 
is richer in warm climates, in dry seasons, and when the cow is 
not too frequently milked. It is said to be richer when cows 
are kept constantly in the house and regularly fed — those which 
go at large in the pasture yielding more cheese. When a cow 
is allowed to go dry for two or three months before calving, it 
is believed to o:ive more milk the following season. In autumn 



318 ADULTERATION OF MILK. 

it is richer upon the whole, giving a less proportion of butter, 
but a greater of cheese ( Aiton, ) while it becomes poorer in both 
when the cow is in calf. The first milk which comes from the 
udder is also poorer than that which is last drawn, the strijp- 
pings or stroakings — and, lastly, the quality of the milk is very 
much affected by the treatment and moral state of the animal. 
Gentle treatment and a state of repose are favorable to the 
richness of the milk ; while anything that frets, irritates or ha- 
rasses the animal, injures its quality. I need scarcely add that 
cleanliness and good ventilation in the cow and milk houses are 
essential to the good flavor of milk. 

SECTION III. OF THE ADULTERATION OF MILK. 

Milk is almost everywhere more or less adulterated with wa- 
ter. In Paris and the neighborhood, the cream is taken off, 
and the skimmed milk thickened with sugar aud an emulsion of 
sweet almonds and hemp-seed, (Raspail.) Skim milk may 
also be thickened with magnesia, and by this means the thick- 
ness of cream may be given to new milk, while it will also be 
kept longer sweet. Common soda or pearl ash is sometimes 
added to milk which has turned, to restore its sweet taste. 

But the most singular adulteration of which I have heard is 
that of mixing up the skim milk with calf's and sheep's brains. 
This mixture renders it thick and rich, and causes a coating, 
apparently of cream, to rise to the surface, which it requires a 
nice chemical examination to distinguish from genuine cream.* 

* The method of examuiation is to treat the creamy matter with ether, 
and to boil what the ether takes up with water containing a little sulphuric 
acid. If the cream is not genuine, the acid solution will then give with 
lime or baryta traces of phosphoric acid. 



THE CHURNING OF CREAM, 319 



SECTION IV. OF THE COMPOSTTION OF CREAM AND THE CHURNING 

OF BUTTER. 

1. Cream. — When milk is left at rest for a length of time, 
the fatty matter which floats in it in the form of minute 
globules, rises to the surface in the form of cream. The rapi- 
dity with which.it thus rises to the surface depends upon the 
temperature to which it is exposed — being quicker in warm 
than in cold weather. Thus, for example, when milk is set 
aside it may be perfectly creamed in 

Hours. Degrees, F. 

36 when the temperature of the air is 50 
24 .. .. 55 

18 to 20 . . . . 68 

10 to 12 .. .. ^7 

while at the temperature of 34° to 3t° F.,— a little higher 
than the freezing point of water, — milk may be kept for three 
weeks without throwing up any notable quantity of cream. 

If the milk when new is placed in a hot basin, and covered 
over with another, the cream is thrown up more quickly, and a 
larger quantity of butter is obtained. Of course, the skimmed 
milk will be so much the poorer. 

The cream thus thrown up contains the greater part of the 
fatty matter of the milk, mixed with a small proportion of the 
curd and much water. Cream of good quality in this country, 
when skilfully churned, will yield about one-fourth of its weight 
of butter; or, one wine gallon of cream weighing 8 J lb, will 
give nearly 2 lb. of butter, 

2. Chioniing. — When milk or cream is agitated for a length 
of time, the fatty matter gradually separates from the milk, 
and collects in lumps of butter. There are several circum- 
stances in connection with the churning to which it is of inte- 
rest to attend. 

a. In the churning of crea7?i it is usual to allow the cream to 



8^0 TEMPEKATURE FOR CREAM. 

stand in cool weather for several days, until it becomes dis- 
tinctly sour. In this state the butter comes sooner, and more 
freely. The butter, when collected in lumps, is well beat and 
squeezed from the milk. In some places it is usual also to 
wash it in cold water as long as it renders the water milky; in 
other places the remaining milk is separated by repeated 
squeezings, and by drying with a clean cloth. 

h. Clouted cream may be churned with advantage in the 
sweet state — the butter separating from it with great ease. 
Colonel le Couteur states that, in Jersey, it is usual to make ten 
pounds of hitter in five minutes from the clouted cream of the 
Jersey or Alderney cow. Clouted cream is obtained^ by gra- 
dually heating the milk in deep pans, almost to boiling, but so 
as never to break the skin or clout that forms on the surface. 
The cream is said to be more completely separated by this pro- 
cess than by any other, and a larger quantity of butter to be 
obtained from the milk. 

c. The tvhole milk may also be churned, after being allowed 
to stand till it has attained the proper degree of sourness, which 
is indicated by the formation of a stiff brat on the surface, 
ickich has become uneven. This method is more laborious, re- 
quiring more time than when the cream only is used ; but it has 
the advantage, as many practical men have found, of yielding 
five per cent more butter from the same quantity of milk, and 
of a quality which never varies in winter or in summer. It also 
requires no greater precautions or more trouble to be taken in 
warm than in cold weather. 

d. Temperature. — This latter advantage is derived from the 
circumstance, that the temperature at which the whole milk 
ought to be churned is higher than that of the air in our cli- 
mate, throughout nearly the whole course of the year. The 
temperature at which milk can be churned most economi- 
cally is about 65° F., a degree of heat which the air seldom 
attains in our warmest summer mornings. The dairy-maid has 
simply to add hot water enough to the milk to raise it to 65° 



TIME REQUIRED FOR CHURNING. 321 

F., and to repeat this every morning of the year, if she churns 
so often. On the other hand, the temperature of cream, when 
churned, should not be higher than from 53° to 55° F., a tem- 
perature beyond which the air often rises. It becomes neces- 
sary, therefore, in summer, to cool the railk-room in which the 
cream is churned, and, by churning early in the morning, to en- 
deavor to keep the cream down to the proper temperature. 

Thus, in churning cream, the task of the dairy-maid is a 
more difficult one. In winter, she must add hot water to bring 
the temperature up to 55°, and in summer must apply cold, to 
keep it down. In this she sometimes fails, and on these occa- 
sions the quality of the butter suffers. 

e. The time required for churning the whole milk in the ordi- 
nary churn is from three to four hours, while the cream alone 
can be churned in about an hour and a half. A churn, how- 
ever, has lately been introduced which churns both milk and 
cream in a much shorter period of time. It is made of tin, is 
of a barrel shape, and is placed in a trough of water, which is 
heated to the temperature the milk or cream ought to be 
brought to. In this churn the butter was extracted from 
cream, at the temperature of 

5G- F. in 60 minutes, . . .\ Butter was harder but no 
' ( better than the lollowing. 

58° F. in 10 to 20 minutes, . Butter excellent. 



60< 



F. in 5 to 7 minutes, . \ ^^^\^^ fi''f'^ "f^ °^ ^^^^^ 
' ( color and quality. 



The whole milk in this churn gave the butter in one hour to 
one hour and a half. Mr. Burnett of Gadgirth informs me, 
that he obtains in this churn a larger quantity of butter from 
the cream than from the whole milk. Thus, from 508 quarts 
of milk — the produce of five cows in one week of July (1843) 
— he obtained, on churning the whole milk, 36 lb. 11 oz. The 
cream, on the other hand, yielded by an equal quantity of milk 
drawn from the same cows during another week, gave him 3t lb. 
4 oz., being a difference of 9 ounces, or about 3 per cent in 



SMALL BREEDS GIVE MOST BUTTER. 

favor of the cream, which is contrary to general experience 
with the ordinary churn, as stated in the previous page. 

Other persons who have tried this churn have not been so 
successful in the use of it as Mr. Burnett. Where they have 
obtained the butter much sooner than usual, they have found 
reason to complain of its quality. Perhaps in these cases the 
churn has not been skilfully used, or something may depend 
upon the quality of the milk — since the cream from the milk of 
some cows is said in the ordinary churn always to come to but- 
ter in ten minutes or less. 

The air ckurn — a still more recent invention — which agitates 
the milk, by forcing a current of air through it, is said to bring 
the butter in the still shorter period of four minutes. 

/. The largest quantity of butter from a given weight of the 
same food, and the richest milk, is yielded by the milk of the 
smaller races. The small Alderney, or Jersey, West Highland, 
and Kerry cows, give a richer milk even than the small Ayr- 
shire. But the small Shetlander is said to surpass them all. 
These breeds are all hardy, and will pick up a subsistence from 
pastures on which other breeds would starve. 

The quantity of butter yielded by different cows in the same 
yard, and eating the same food, is sometimes very different. 
Some will yield only 3 or 4 lb. a week, while more will give 
8 or 9 lb., and a few 15 lb. a-week. As a rare instance, I may 
mention that a cow has been known in Lancashire to yield up- 
wards of 22 lb. in seven days. 

SECTION V. — OF THE QUALITY, COMPOSITION, PRESERVATION, AND 
COLORING OF BUTTER. 

1. The quality of butter varies with numerous circumstances. 

The kind of natural pasture, or of artificial food, upon which 

the cow is fed, the season of the year, the breed, the individual 

constitution and state of health of the animal, the mode of 

14* 



QUALITY OF IJUTTER VARIES. 323 

churning, the cleanliness of the cow and milk houses, &c., all 
more or less affect the quality of the butter. 

But from the same cow, fed on the same food, and in the 
same circumstances, a richer l)utter, and of a finer and higher 
flavor, will be obtained by churning the last drawn portions of 
the milk. So the first cream that rises gives the finest flavored 
butter, — while any cream or milk will give a butter of better 
quality if it be- properly soured before it is churned, and be 
then churned slowly and at a low temperature. 

2. Tht composition of butter. — Butter, as it is usually brought 
to the market, contains more or less of all the ingredients of 
milk. It consists, however, essentially of the fat of milk, inti- 
mately mixed with about one-eighth of its weight of water, 
and a small quantity of casein or curd, of saline.matter, alld of 
the sugar of milk. The quantity of casein (cheesy matter or 
curd) seldom amounts to one per cent of the whole weight of 
the butter. 

If the butter be melted in hot water several times, shaken, 
with renewed portions of water as long as they become milky, 
and left then to repose, it will collect on the surface in the 
form of a fluid yellow oil, which will concrete or harden as it 
cools. If when cold it be put into a linen bag, and be sub- 
mitted to strong pressure in a hydraulic or other press, at tho 
temperature of 60° F,, a slightly yellow transparent oil will 
flow out, and a solid white fat will remain behind in a linen 
cloth. The solid fat is known by the name of margerine, and 
is identical with the solid fat of the human body, with that of the 
goose, and with that which causes the thickness of olive oil 
when exposed to the cold. It is very similar also to the solid 
fat of palm oil. The liquid or butter oil is a peculiar kind of 
fat not hitherto discovered in any other substance. 

The proportion of these two kinds of fat in butter varies con- 
siderably, and hence the different degrees of hardness which 
different samples of butter present. The solid fat is said to 
abound more in winter, the liquid fat in summer. Winter and 



324 SOLID AND LIQUID FATS IN BUTTER. 

summer samples of butter manufactured in the Vosges were 
found to contain per cent respectively of 

Summer. "Winter. 
Solid (at or margerine, . . 40 65 

Liquid fat or butter oil, . . 60 35 

100 100 

These proportions, however, will be found to vary more or 
less in almost every sample of butter we examine. 

In Jersey, the drainings of the curd in rich-cheese making 
give a butter which is inferior for eating with bread, but very 
superior for pastry. It is peculiarly hard, and fitted for such 
use in hot weather. It probably contains more of the solid fat 
of butter. 

3. The preservation of butter. — Fresh butter cannot be kept 
for any length of time in our climate without becoming rancid. 
The fats themselves undergo a change ; and the same is the 
case with the small quantity of milk sugar which the butter 
contains. The main cause of this change is the casein or curd 
which is usually left in the butter. The proportion of this 
cheesy matter I have found in two samples of fresh butter to 
vary from one-half to three-fourths of a per cent, — or from half 
a pound to three-quarters of a pound in 100 pounds of butter; 
and yet this small quantity is sufincient, if the ])utter be expos- 
ed to the air, to induce those chemical decompositions to which 
the disagreeable smell and taste of rancid butter are owing. 
The butter made in the pure air of the Alpine valleys of Pied- 
mont and Switzerland, after a complete expression of the milk, 
is said to be " preserved sweet, or at least fit for use, through 
the whole season, without any admixture of salt.-' By melting 
and skimming the butter also, and then pouring it hot into a 
jar, it is in Switzerland preserved without salt. In this latter 
state it is called boiled butter, {huerre cuit,) and is chiefly used 
for cookery.* 

* Fhysician's Holiday, by Dr. Egrbes, p. 336. 



HOA? BUTTER BECOMES RANCID. 325 

I do not enter here into the theory of the action of this 
casein, nor into an explanation of the nature of the chemical 
eha-nges themselves.* It is sufficient to state, that this evil 
action of the cheesy matter may be entirely prevented. 

a. By salting immediately after the butter is made, and be- 
fore the cheesy matter has had time to become altered by ex- 
posure to the air. 

h. By taking- care that any water which may remain in or 
around the butter be always kept perfectly saturated with salt. 

c. By carefully excluding the air from the casks or other ves- 
sels in which the butter is packed. 

So long as the cheesy matter is kept from the air, and in a 
saturated solution of salt, it will neither undergo any rapid 
alteration itself, nor will it soon induce any offensive alteration 
in the butter. 

About half a pound of salt is used to 12 or 14 lb. of butter ; 
but when salted for exportation, or for the use of the navy, one 
pound of salt is added to 10 or 12 of butter. Though many 
wash their butter, it is a rule with others never to wash it or dip 
it into loater when intended to he salted, but to work it with cool 
hands till the butter milk is thoroughly squeezed out, and then- 
to proceed with the salting. Theoretically, I should consider 
this latter the better plan, since it exposes the cheesy matter 
less to the air, and consequently to less risk of incipient decom- 
position. 

Some fancy they cure their butter better by dissolving the 
salt in the cream before churning, while many consider its pre- 
servation and good quality to depend much upon the quality of 
the salt that is employed. 

Some prefer, instead of salt alone, to make use of a mixture 
of one part of sugar, one of nitre, and two of salt ; and some 
who use an impure salt, consider the butter to be improved by 
washing it in a saturated solution of salt. 

* The reader will find these fully explamed in the Author's published 
Lectures on Agricultural Chemistry and Geology^ 2d edit., p. 976. 



326 SOURING OF MILK. 

It is said that rancid butter maybe rendered sweet by churn- 
ing it with fresh sweet milk, in the proportion of six pounds of 
butter to the gallon. 

4. Coloring butter. — Butter is sometimes colored, and the 
juice of scraped carrots is not unfrequently employed for the 
purpose. 

BECTION VI. OF THE SOURINU OF MILK, OF MILK-SUGAR, AND OF 

THE ACID OF MILK. 

1. When milk is left to itself for a sufiicient length of time, 
it becomes sour and curdles. This takes place sooner in warm 
weather, and in vessels which have not been cleaned with suffi- 
cient care. 

Why does milk thus become sour ? 

a. Sugar of Milk. — I have already stated that milk contains 
a quantity of a peculiar kind of sugar, found only in milk, to 
which, therefore, the name of milk-sugar is given. It differs 
from common cane sugar in being harder, less sweet, and much 
less soluble in water. Of this sugar, miUc contains generally a- 
larger jproportion than it does of either fat or curdy (p. 313). A 
gallon of milk, therefore, would yield a greater weight of sugar 
than it does of either butter or cheese. In this country, the 
sugar is usually neglected. In our cheese districts, it is given 
to the pigs, and sometimes to the cows in the whey with which 
they are fed. In Switzerland and elsewhere, it is extracted as 
a profitable article of commerce, 

h. Acid of milk, — When milk becomes sour, a peculiar acid 
is formed in it, to which, from its having been first observed in 
milk, the name of lactic acid, or acid of milk, has been given. 
To this acid the sourness of milk is owing. The same acid is 
produced when crushed wheat — as in the manufacture of starch 
from wheat — wheaten flour, oat-meal, pease-meal, &c., or when 
cabbage and other green vegetables are mixed with water, aud 



SUGAR AND ACID OF MILK. 32 1 

allowed to become sour. It exists also in small quantity in the 
acorn, (p. 289.) 

c. But how is iha add produced ? — As the acid of milk in- 
creases in quantity, the sugar of milk diminishes. The acid, 
therefore, is formed from or at the expense of the sugar. There 
is no fermentation, and therefore no loss of matter : the sugar 
is merely transformed into the acid, and by a process the out- 
line of which it is very easy to understand. Like cane sugar, 
grape sugar, and gum, (p. 43,) both may be represented by, 
or may be supposed to consist of, carbon and water, and in the 
same proportions. Thus. — 

Carbon. Water. 

Sugar of milk consists of . .6 and 6 

Acid of milk, {lactic acid,) . . 6 and 6 

The same particles of matter, therefore, which compose the 
sugar, are made to assume a new arrangement, and, instead of 
a sweet sugar, to form a sour acid. In the interior of the milk, 
nature takes down and builds up its materials at her pleasure, 
— using the same molecules to form now this and now that kind 
of substance — as the child plays with its wooden bricks, erect- 
ing a hut or a temple with the materials of a ruined palace or 
a fallen bridge. So nature seems to play with her materials, — 
working up all, wasting none, — yet so skilful in all her opera- 
tions as to excite our wonder, so secret as not unfrequentl^ to 
escape our observation, and so quick as often to show that she 
has been working, only by the striking effects she has produced. 
To the simple peasant and to the instructed philosopher, it is 
equally a matter of wonder, and almost equally unintelligible, 
that the same number of material particles arranged in one way 
should affect the organs of taste with the sweetness of sugar, 
in another with the sourness of lactic acid. 



328 WONDERFUL CHANGES OF FORM. 



SECTION VII. OF THE CURDLING OF MILK, OF CASEIN, AND OF THE 

ACTION OF RENNET. 

As milk becomes sour, it also thickens or curdles. If it he 
then slightly heated, the curd runs together more or less, and 
separates from the whey. If the whole be now thrown upon 
a linen cloth and gently pressed, the clear whey will run through 
and the curd will remain on the cloth. This curd, when salted, 
pressed, and dried, forms the cheese which we consume so ex- 
tensively as an article of food. 

In consequence of what chemical change does this separation 
of the curd take place ? 

1. It is to be borne in mind, that this curdling does not take 
place naturally till the milk has become sour. The acid of the 
milk, therefore — the lactic acid — has some connection with the 
separation of the curd. It is, in fact, the cause of the curd- 
ling. 

2. But, in order to understand how this is, we must turn for 
a moment to the properties of the curd itself. Chemically pure 
curd or casein is a protein compound, which contains less sul- 
phur than albumen does, and no phosphorus, (p. 46.) 

a. When the curd of milk is separated carefully from the 
whey, it may be washed or even boiled in water, without being 
sensjbly lessened in quantity. Pure curd is nearly insoluble in 
jpure water. 

b. But if a little soda be added to the water in which the 
curd is heated, it will dissolve and disappear. Pure curd is 
soluble in a solution of soda. 

c. If to the solution of the curd in soda and water a quanti- 
ty of the acid of milk be added, this acid will combine with the 
whole of the soda — will take it from the curd, which will thus 
be again separated in an insoluble state. The curd is insoluble 
in water, rendered sour by the acid of milk. 

These facts explain very clearly the curdling of milk. As it 



WHY THE CURD SEPARATES. 329 

comes from the cow, milk contains a quantity of soda not com- 
hiimi loith a7iy add, by which soda the curd is believed to be 
held in solution. As the milk becomes sour, this soda combines 
with the lactic acid produced, and thus the curd becoming in- 
soluble separates from the whey — or the milk thickens and 
curdles. 

Now, the effect which is thus produced by the natural for- 
mation of lactic acid in the milk, may be brought about by the 
addition of any other acid to it — such as vinegar or spirit of 
salt. And, in fact, vinegar is used now, in some countries, and 
in ancient times was used more extensively, for curdling milk ; 
while in some of the cheese districts of Holland, spirit of salt 
(muriatic acid) is said to be employed for the same purpose. 
Sulphuric acid has been also recommended, but has been found 
to give the cheese an unpleasant taste. 

3. But in most dairy countries rennet is the substance used 
for the curdling of milk. What is rennet ? and how does it 
act? 

a. The stomach of the calf, of the kid, of the lamb, of the young 
pig, and even of the hare,* when covered with salt, or steeped for 
some time in water perfectly saturated with salt and then dried, 
forms the dried maw-skin or bag which is used for the prepara- 
tion of rennet. If the dried skin of nine or ten months old be 
steeped in salt and water, a portion of its substance dissolves, 
and imparts to the water the property of coagulating milk. 
The water thus impregnated forms the rennet or yirning of the 
dairy-maid. In some districts it is usual to steep several skins 
at once, and to bottle the solution for after use — mixed with 
more or less brandy, whisky, or other spirit. In others, a por- 
tion of the dry skin, sufficient to make the quantity of rennet 
required, is cut off the night before, and steeped in water till 
the milk is ready in the morning. To this solution many dairy- 

* Three hares' stomachs are considered equal to one calf's. 



330 HOW RENNET ACTS. 

maids add a quantity of strong spirit before putting it into the 
milk, which probably increases its coagulating power. 

h. The rennet thus prepared coagulates more or less readily, 
according to its strength. On what priiiciple does it act ? 

If a piece of the fresh membrane of the calf's stomach or 
intestine, or even if a piece of fresh bladder, be exposed to the 
air for a short time, and be then immersed into a solution of 
milk-sugar, it gradually causes the sugar to disappear, and to 
change into lactic acid — the acid of milk. If the salted and 
dried memt)rane be employed instead, it will produce the same 
effect, only with greater rapidity. 

But, by long exposure to the air in drying the surface, the 
salted membrane undergoes such a change, that a portion of it 
becomes soluble in water, yet still retains or acquires, even in a 
higher degree, the -property of changing milk-sugar into the 
acid of milk. It is this soluble portion which exists in the 
liquid rennet. 

Now, the same effects which the membrane produces upon 
the sugar of milk alone, it produces also upon the sugar as it is 
contained naturally in the milk — in other words, the rennet, 
when added to the warm milk, changes the sugar into the acid of 
milk. This it effects more or less rapidly according to circum- 
stances, and hence the different length of time which elapses in 
different dairies before the milk is fully thickened. 

c. The addition of rennet, therefore, is only a more rapid way 
of making the milk sour, or of converting its sugar into lactic 
acid. The acid produced, as in the natural souring of milk, 
combines with the free soda, and renders the cheesy matter in- 
soluble, which, in consequence, separates ; — in other words, the 
milk curdles. The milk, it is true, does not become sensibly 
sour, because the production of acid in a great measure ceases 
as soon as the soda of the milk is fully saturated with the acid ; 
and if any excess of acid be produced, it is taken up and ab- 
sorbed or separated in and by the curd, so as to leave the whey 
comparatively sweet. Even the rennet that is added is carried 



MANUFACTURE OF CHEESE. 331 

off by the curd, which is thus often injured in quality if too 
much rennet have been added, or if its smell or taste have been 
unpleasant. The sugar that remains in the whey is thus ena- 
bled to retain its sweetness — that is, to remain unchanged into 
acid — longer than it could have done had any excess of rennet 
remained in it after the separation of the curd. 

The chemical change produced by rennet in curdling milk, 
therefore, is precisely the same as that which takes place when 
milk sours naturally. In both cases the lactic acid which is 
formed causes the milk to curdle. 



SECTION VIII. OF THE MANUFACTURE AND THE QUALITY OP 

CHEESE. 

1. TJie. manufacture of cheese is, generally speaking, con- 
ducted in the same manner in all countries. The milk is 
curdled by the addition of rennet, vinegar, muriatic acid 
(spirit of salt,) lemon juice, tartaric acid, cream of tartar, 
salt of sorrel, — by sour milk even, as in some parts of Switzer- 
land,* or by the decoction of certain plants or flowers, as of those 
of the wild thistle, employed for the ewe cheeses of Tuscany. 

The curd is then more or less carefully separated from the 
whey, tied up in a cloth, and exposed to gentle pressure. In 
general, the curd at this stage is broken small, and mixed with 
a due proportion of salt before it is allowed to consolidate and 
dry. For the thin cheeses of Gloucester and Somerset, how- 
ever, this mode of salting is not adopted, the whole of the 
salt that is necessary being afterwards rubbed in and made to 
penetrate through the exterior of the cheese. 

After it is removed from the press, the cheese is rubbed over 

* It is stated bj old cheese-makers in Nottinghamshire, that churned 
milk added to cheese milk in the usual way, very much unproves both the 
quality and taste of the cheese, and prevents it from rising after it is 
made. 



332 THE QUALITY OF THE CHEESE 

with salt, or is covered with a layer of it — at a later period is 
more or less frequently anointed with butter, is kept for a 
week or two in a rather warmish place, and is frequently 
turned. There are minute details to be attended to, where 
cheese of good quality is desired, with which the skilful and 
experienced dairy-maid is familiar, but upon which it is unne- 
cessary here to dwell. 

2. The quality of the cheese varies with a great variety of 
circumstances, partly natural and unavoidable, but partly also 
to be controlled by art. 

a. Thus there are natural differences in the milk, arising 
from the kind of grass or other food on which the cows are 
fed, which necessarily occasion corresponding differences in the 
quality of the cheese made from it. The milk of different 
animals also gives cheese of unlike qualities. The ewe-milk 
cheeses of our own country, of Italy, and of France, and those 
of goat's milk made on Mount d'Or and elsewhere, are dis- 
tinguished by qualities not possessed by cow's milk cheeses pre- 
pared exactly in the same way. The milk of the buffalo like- 
wise gives a cheese of peculiar qualities, arising, as in the cases 
of the ewe and the goat, from some natural peculiarity in the 
composition of the milk itself. 

h. But every dairy farmer knows that, from the same milk, 
cheeses of very different flavors, and of very unlike values in 
the market, may be made — that the mode of management has 
not much less to do with the peculiar quality of his dairy pro- 
duce than the breed of cattle he uses, or the pasture on which 
his cows are fed. Yery slight circumstances, indeed, affect the 
richness, flavor, and other valuable properties of his cheese. 

Thus if the new milk, when the rennet is added, be warmer 
than 95° F., the curd is rendered hard and tough ; if colder, it 
is soft, and difficult to free from the whey. If heated on the 
naked fire, as is often done, in an iron pot, the milk may, by a 
very slight inattention, become fir e-fanged, and thus impart an 
unpleasant flavor to the cheese. If the curd stand long un- 



IS AFFECTED BY MANY CIRCUMSTANCES. 333 

broken after the milk is fairly coagulated, it becomes bard and 
tough. If the rennet have an unpleasant flavor, or if too much 
be added, the flavor and keeping qualities of the cheese are 
affected. If acids are used instead of rennet, the properties of 
the cheese are altered. It is less rich if the whey be hastily 
and with much pressure squeezed out of the curd ; or if the 
curd be minutely broken up and thoroughly mixed and stirred 
up with the whey, or washed by it, as is the custom in Norfolk 
• — instead of being cut with a knife, so that the whey may 
flow slowly and gently out of it, as is done in Cheshire or Ayr- 
shire — or instead of being placed unbroken upon the cloth, as 
in making Stilton cheese, so that the whey may drain and 
trickle out spontaneously, and may carry little of the fatty mat- 
ter along with it. Some of the Cheshire dairy-maids give their 
cheese a tendency to green mould, by setting or curdling their 
milk at a low temperature ; and the inferiority of Dutch cheese 
is ascribed by some to the custom of soiling or feeding in the 
house, which affects the flavor of the cheese without injuring 
the health of the animal. 

c. The kind of salt also which is used,* the way in which the 
cheese is salted, the size of the cheese itself, and, above all, the 
mode in which it is cured, have very much influence upon its after 
qualities. Hence a fair share of natural ability, as well as long ex- 
perience, are necessary in the superintendent of a large dairy 
establishment, when the best quality of cheese which the milk 
can yield is to be manufactured uniformly, and at every season 
of the year. 

SECTION IX. OF THE VARIETIES OF CHEESE. 

The varieties of cheese which are manufactured are very 

* The kind of salt preferred in the dairy districts of the west of Scotland 
is an impure variety from Saltcoats, which contains a notable quantity ol 
the deliquescent salts, (chlorides of lime and magnesium.) These salts seem 
to keep the skin of the cheese moist, and to assist its stoning. 



334 VARIETIES OF CHEESE. 

numerous, but the greater proportion of these varieties owe 
their peculiar qualities to the mode of management which is fol- 
lowed in the districts or dairies from which they come. IS'atural 
varieties, however, arise under the same general management, 
and from the same milk, according to the state in which the 
milk is used. Thus we have — 

a. Cream cheeses, which are made from cream alone, put into 
a cheese-vat, and allowed to curdle and drain of its own accord, 
and without pressure ; or as in Italy, by heating the cream, 
and curdling with sour whey or with tartaric acid. These 
cheeses are too rich to be kept for any length of time. 

h. Cream and milk cheeses, when the cream of the previous 
night's milking is mixed with the new milk of the morning, be- 
fore the rennet is added. The English Stilton cheeses and the 
small soft Brie cheeses, so much esteemed in France, are made 
in this way. 

c. Whole or full milk cheeses, which, like those of Gloucester, 
Wiltshire, Cheshire, Cheddar, and Dunlop, are made from the 
uncreamed milk. These cheeses, like the preceding, however, 
will be more or less rich according to the way in which the 
curd is treated, and according as the milk is curdled while 
naturally warm, as in the best Ayrshire dairies, and in some 
parts of Holland — or is mixed, as in Cheshire and in some Ayr- 
shire dairies, with the milk and cream of the previous evening. 

The large 60 to 120 lb. cheeses of Cheshire will not stand, 
will break and fall asunder, if all the cream is left in the milk. 
About one-tenth of the cream, therefore, is skimmed off and 
made into butter. About 20 lb. of butter a-week are thus 
made in a cheese dairy of 100 cows. 

d. Half-^ilk cheeses, such as the single Gloucester, are made 
from the new milk of the morning, mixed with the skimmed 
milk of the evening before. 

g. Skimmed-milk cheeses — which may either be made from the 
milk once skimmed, like the Dutch cheeses of Ley den, twice 
skimmed, like those of Friesland and Groningen, or skimmed 



WHEY AND BUTTER-MILK CHEESES. 335 

for three or four days in succession, like the horny cheeses of 
Essex and Sussex, which often require the axe to break them, 
and are sometimes used for certain purposes in the arts,* 

/. Whey cheeses made from the curd which is skimmed off the 
whey when it is heated over the fire. This is by no means a 
poor kind of cheese ; and good imitations of Stilton are said to 
be sometimes made by mixture of this curd with that of the 
whole milk. 

g. Biitter-^iilk cheeses, made by simply straining the butter- 
milk through a cloth, and then either gently heating the butter- 
milk, which causes the curd to separate, or, as is sometimes 
done, by the addition of rennet. This kind of cheese is not 
unworthy of attention, as it is often richer than that made 
from milk only once skimmed. Though it cannot, of course, 
have the richness, it is said to possess some of the other cha- 
racteristic qualities of good Stilton cheese. 

h. Vegetable cheeses are made by mixing vegetable substances 
with the curd. The green Wiltshire is colored by a decoction 
of sage leaves, marigold, and parsley. I do not know if it is 
to this practice, or to one of actually mixing the sage leaves 
with the curd, that Gay alludes in the line — 

" Marbled with sage, the hardening cheese she pressed." 

The Schabzieger cheese of Switzerland is a mixture of the curd 
obtained from the whey of skimmed milk, with one-twentieth of 
its weight of the dried leaves of the mellilot trefoil. f 

i. The Potato cheeses of Saxony and Savoy consist of dry 
boiled potatoes mixed with a half or a third of their w^eight, or 
with any other proportion of the fresh curd, or simply with sour 
or with skimmed milk. The mixture is allowed to undergo a 

* Suffolk cheese, which is locally known by the name of " Suffolk 
Bank," is so hard that " pigs grunt at it, dogs bark at it, but neither of 
them dare bite it." 

f Zkger is the curd separated from whey either by a fresh addition of 
acid or in some other way. 



336 POTATO CHEESE. 

species of slight fermentation before it is made up into shapes. 
Such cheeses, when well cured, are said to form a very agree- 
able article of diet, and to be capable of being kept for a long 
period of time.* 

* For farther details in regard to milk and its products, the reader is re- 
ferred to the Author's Lectures on Agricultural Chemistry and Geology, 2d 
edition, pp. 928 to 1008. 



CHAPTER XXlV. 

On the feeding of animals. — Main visible functions of the living animal. — 
The food must supply the wants of resph-ation. — Nature, wants, and pur- 
poses of this function. — The daily waste of the muscular parts and tissues 
of the body. — Food necessary to repair it. — Saline and earthy matters 
contained in its several parts, and daily rejected by the body. — Waste or 
increase of fat supplied by the food. — Special waste in the perspiration. 
— Forms in which the solid matter of the tissues escapes in the urine of 
animals. — G-eneral balance of food and excretions. — Kind of food re- 
quired, as indicated by the composition of the blood. — Importance of a 
mixed food. 

The food of plants we have seen to consist essentially of two 
kinds, the organic and the inorganic, both of which are equally 
necessary to the living vegetable — equally indispensable to its 
healthy growth. A glance at the purposes served by plants in 
the feeding of animals, not only confirms this view, but throws 
also additional light upon the kind of inorganic food which 
plants must be able to procure, in order that they may be fitted 
to fulfil their assigned purpose in the economy of nature. 

SECTION I. MAIN VISIBLE FUNCTIONS OF LIVING ANIMALS. 

Man, and all domestic animals, may be supported, may even 
be fattened, upon vegetable food alone. Vegetables, therefore, 
must contain all the substances which are necessary to build up 
the several parts of animal bodies, and to supply the waste at- 
tendant upon the performance of the necessary functions of ani- 
mal life. 

All living animpJs perform three main or leading functions 
necessary to the continuance of healthy life. 
15 



338 FUNCTIONS OF THE LIVING ANIMAL. 

1°. They breathe, alternately inhaling and exhaling air by 
means of the lungs. 

2°. They digest, dissolving the food in the stomach, and se- 
lecting from it the materials necessary to form blood. 

30. They excrete, rejecting in the solid excretions and the 
urine, or giving off from the skin and the lungs — 

a. That part of the food which cannot be dissolved and 
made use of as it passes through the alimentary canal. 

h. The materials derived from the decomposed tissues or 
parts of the body vrhich are undergoing a constant waste. 

To the wants of an animal performing these visible functions 
in a healthy and regular manner, the food must be adapted in 
kind and quantity. I shall briefly illustrate what these wants 
demand. 

To the numerous minor and invisible functions performed 
within the' several parts of the living body, it is unnecessary to 
advert in detail. I may have occasion incidentally to advert 
to one or two of the more interesting of these ; l)ut as a 
healthy blood contains all that is necessary to the discharge of 
these functions, it would only complicate our present inquiry to 
consider their several direct relations to the undigested food as 
it is introduced into the stomach. 

SECTION II.-THE FOOD MUST SUPPLY THE WANTS OF KESPIRATION. 

NATURE, WANTS, AND PURPOSES OF THIS FUNCTION. 

While an animal lives it breathes. It alternately draws in 
and throws out atmospheric air by means of its lungs. 

1. When this air enters, it contains about two gallons of 
carbonic acid in every 5000 ; when it escapes from the lungs it 
contains 2 gallons or upwards in every 100. The proportion is 
increased from 50 to 100 times. Much carbonic acid, there- 
fore, is given off from the lungs of animals during breathing. 
In other words, living animals are continually throwing off car- 



CARBON GIVEN OFF BY THE LUNGS. 339 

bon into the air, since carbonic acid contains about two-sevenths 
of its weight of solid carbon, (p. 20.) 

A man of sedentary habits, or whose occupation requires lit- 
tle bodily exertion, may throw off in this way about five ounces 
of carbon in twenty-four hours — one who takes moderate exer- 
cise, about 8 ounces — and one who has to undergo violent bodily 
exertion, from 12 to 15 ounces. In our climate about one-fifth 
more is given off in summer than in winter. 

If we take the mean quantity respired at 8 ounces, then, to 
supply this carbon alone, a man must eat 18 ounces of starch 
and sugar every day.* If he take it in the form of wheaten 
bread, he will require 1| lb. of bread ; if in the form of pota- 
toes, about 7 J lb. of raw potatoes to supply the carbon which 
escapes through his respiratory organs alone. 

When the habits are sedentary, 5 lb. of potatoes may be 
sufficient ; when violent and continued exercise is taken, 12 to 
15 lb. may be too little. At the same time, it must be observed 
that when the supply is less, either the quantity of carbon gi- 
ven off will be less also, or the deficiency will be supplied at 
the expense of the body itself, especially its fatty part. In 
either case the strength will be impaired, and increased supplies 
of nourishing food will be required to recruit the exhausted 
frame. 

'Other animals give off from their lungs quantities of carbon 
proportioned to their weights. A cow or a "liorse, eight or ten 
times the weight of a man, will give off 4 to 5 lb. of carbon. 
The quantity of food required to supply this carbon will be pro- 
portionably greater. 

I have in the above calculations supposed that the vfhole of 
the carbon given off from the lungs is derived from the starch, 
sugar, or gum of the food. This view is the simplest, and most 
easily intellegible. It only requires us to suppose that in the 
system the starch is separated into carbon and water, of whicli, 

* Since 12 lb. of starch contain about 5 lb. of carbon, (see p. 43.) 



340 THE BODY FED BY OXYGEN. 

as we have seen, (p. 43,) it may be represented to consist ; and 
that the former is given or burned off from the lungs in the 
form of carbonic acid. But many physiologists do not regard 
the process as being really so very simple. They consider that 
the carbon given off is partly derived from the gluten or flesh 
of the food, as well as from the starch or fat — in which case 
the quantity of starch or sugar in the food, as I have calculated 
it, need not be so large ; and it is certain that where animals 
live on food which contains no starch or sugar, and but little 
fat, the gluten or fleshy fibre it contains must yield the carbon 
which is given off by the lungs. 

2. But when the air escapes from the mouth of a breathing 
animal, it contains much moisture also. It enters comparatively 
dry, it comes out so moist as readily to deposit dew upon any 
cold surface, or to form a white mist in a wintry atmosphere. 
This water is given off by the lungs, along with the carbonic 
acid, and, like it, is derived from the food, solid or liquid, which 
has been introduced into the stomach. It may either be part 
of the water which has been swallowed as such, or the water 
which may be supposed to exist in the starch and sugar of the 
food. Or it may be water formed by the union of the hj^dro 
gen of the other kinds of food with the oxygen inhaled by the 
lungs. It is probably derived in part from each of these sour- 
ces, in proportions which must vary with many circumstances.* 

3. But the lungs actually feed the body. The air which en- 
ters contains more oxygen than when it returns again from the 
lungs. The oxygen which disappears equals in bulk very near- 
ly that of the carbonic acid which is evolved. This oxygen 
enters the lungs, through them into the blood, and with the 
blood flows on and circulates through the body. It also en- 
ters partly into the composition of the tissues, so that it is a 
real food, and is as necessary to the construction of the human 
body as the other forms of food which are usually introduced 
into the stomach. The weight of oxygen taken up by the 



DAILY WASTE OF TISSUES. 341 

lungs exceeds considerably that of all the dry solid food which 
is introduced into the stomach of a healthy man. (See p. 38t.) 
4. The purposes served by the oxygen thus introduced into 
the S3^stem are very difficult and complicated. But an inciden- 
tal circumstance, which accompanies all its operations in the 
system, is the evolution of heat. From the time the solid di- 
gestible food enters the blood till it escapes from the lungs, or 
in the other excretions, it is continually uniting with oxygen 
into new forms of combination, and at each change heat is 
produced or given off. Thus the animal heat is kept up, and 
thus it is, in a certain sense, correct to say that oxygen is taken 
in by the lungs for the purpose of giving warmth to the body, 
— or, more poetically, that the body is a lamp fed with oil from 
the stomach, and with air from the lungs, w^hich burns with a 
slow and invisible flame, but which ever does burn while life 
lasts, and maintains a gentle warmth through all its parts. 

SECTION III. — THE FOOD MUST REPAIR THE DAILY WASTE OF THE 
MUSCULAR PARTS AND TISSUES OF THE BODY. 

From every part of the growing as well as of the full-grown 
body, a portion is daily abstracted by natural processes, and re- 
jected either throtigh the lungs and skin, or in the solid and 
fluid excretions. This proportion is so great that in summer 
the body loses one-fourteenth, and in winter one-twelfth of its 
weight daily, when no food is taken. And if food be continu- 
ously withheld, the mean duration of life is only fourteen days, 
and the weight diminishes two-fifths. But the waste or change 
of material proceeds more rapidly when the animal is well fed, 
so that the opinion now prevails among physiologists that every 
twenty or thirty days the greater part of the matter of the hu- 
man body, when adequately fed, is constantly renewed. This 
waste of the tissues is more rapid in women than in children, in 
men than in women, and most of all in men between the ages, 
of 30 and 40. The amount of waste is the measure of life. 



342 coMPOsmo!T op fibrin. 

The materials for this change must be supplied by the food 
And the quantities required must be adapted to the nature, 
age, and sex of the animal. 

The muscles of animals, of which lean beef and mutton are ex- 
amples, are generally colored by blood ; but when washed with 
water for a length of time, they become quite white, and, with 
the exception of a little fat, are found to consist of a white fibrous 
substance, to which the name oi fibrin has been given by chem- 
ists. The clot of the blood consists chiefly of the same sub- 
stance ; while skin, hair, horn, and the organic part of the 
bones, are composed of varieties of gelatim. This latter sub- 
stance is familiarly known in the form of glue, and though it 
differs in its sensible properties, it is remarkably similar to fihrin 
in its elementary composition, as well as to the white of the 
tgg, {albumen,) to the curd of milk, (casein,) and to the gluten 
of flour. They all contain nitrogen, and the three latter con- 
sist of the four organic elementary bodies very nearly in the 
following proportions : 

Carbon, ...... 55 

Hydrogen, ...... 7 

Nitrogen, . . . • , . .16 

Oxygen, with a little sulphur and phosphorus, . 22 

100 

Gelatine or dry glue contains about 2 per cent more 
nitrogen. 

The quantity of one or other of these substances removed 
from the body in 24 hours, either in the perspiration, (p. 369,) 
or in the excretions, amounts to about five ounces, containing 
350 grains of nitrogen ; and this waste at least must be made 
up by the gluten, fibrin, or other protein compounds of the 
food. 

In the 1| lb. of wheaten bread, supposed in the previpus 
section to be eaten to supply the carbon given off by the lungs, 
there will be contained also about 3 ounces of gluten — a sub- 



FOOD CONSUMED, 343 

stance nearly identical with fibrin^ and capable of taking its 
place in the animal body. Let the other two ounces which are 
necessary to supply tlie daily wj^ste of muscle, &c., l)e made up 
in beef, of which half a pound contains 2 ounces of dry fibrin, 
and we have- — 

For For waste 

respiration. of muscle, &c. 

1| lb. of bread yielding 18 oz. starch and 3 oz. of gluten. 
8 oz. of beef yielding . . 2 oz of fibrin. 



Total consumed by I ( gluten or 

respiration and the >• 18 oz. starch and 5 oz.- -j ^'^j^j-j^^ 
ordinary waste, ) 

If, again, the 1\ lb. of potatoes be eaten, then in these are 
contained about 2^ ounces of ghiten or albumen, so that there 
remain 2^ ounces to be supplied by beef, eggs, milk, or cheese. 

The reader, therefore, will understand why a diet, which will 
keep up the human strength, is easiest compounded of a mix- 
ture of vegetable and animal food. It is not merely that such 
a mixture is more agreeable to the palate, or even that it is ab- 
solutely necessary — for, as already observed, the strength may 
be fully maintained by vegetable food alone ; — it is because, 
without animal food in one form or another, so large a bulk of 
the more common varieties of vegetable food requires to be 
consumed in order to supply the requisite quantity of nitrogen 
in the form of gluten, albumen, &c. Of ordinary wheateu 
bread alone, about 3 lb. daily must be eaten to supply the ni- 
trogen,* and there would then be a considerable waste of car- 
bon in the form of starch, by which the stomach would be over- 
loaded, and which, not being worked up by respiration, would 
pass off in the excretions. The wants of the body would be 

* The dry flour being supposed to contain 15 per cent of dry gluten, 
(a large proportion,) on which supposition all the above calculations arc 
made. 



344 SALINE MATTER OF FLESH AND BLOOD. 

equally supplied, and with more ease, by 1| lb. of bread, and 4 
ounces of cheese. 

Oatmeal, again, contains at least one-half more nitrogen 
than the wheaten flour of our climate (p. 283,) and hence 21b. 
of it will usually go as far in supplying this portion of the na- 
tural waste as 3 lb. of wheaten flour, and the stomach will be 
less oppressed. This fact throws much light on the use and 
value of what has been called the natural food of Scotland. 

The stomach and other digestive apparatus of our domestic 
animals are of larger dimensions, and they are able, therefore, 
to contain with ease as much vegetable food, of almost any 
wholesome variety, as will supply them with the quantity of ni- 
trogen they may require. Yet every feeder of stock knows 
that the addition of a small portion of oil-cake, or of bean- 
meal, substances rich in nitrogen, will not only fatten an ani- 
mal more speedily,, but will also sa,ve a large hulk of other 
kinds of food. 



SECTION IV. THE FOOD MUST SUPPLY THE SALINE AND EARTHY 

MATTERS CONTAINED IN AND DAILY REJECTED BY THE BODY. 

The full-grown animal daily rejects a quantity of saline and 
earthy matter withdrawn from its wasting tissues ; while the 
growing animal appropriates also every day an additional por- 
tion in the formation of its increasing parts. The food must 
yield all this, or the functions will be imperfectly performed. 

1. Thejiesh, the hlood, and the other ftuids of the body con- 
tain much saline matter of various kinds — sulphates, muriates, 
phosphates, and other saline compounds of potash, soda, Hme, 
and magnesia. The dry muscle and blood of the ox leave, 
when burned, about 41 per cent of saline matter or ash. The 
composition of this saline matter is represented in the follow- 
ing table of Enderlin : — 



MINERAL MATTERS IN THE BODY. 345 



Phosphate of soda, (tribasic,) . 

Chloride of sodium, (common salt,) 

Chloride of potassium, . 

Sulphate of soda, 

Phosphate of magnesia, 

Oxide, with a little phosphate of iron, 

Sulphate of lime, gypsum, and loss, 



Blood. 


Flesh. 


16.77 


45.10 


59.34 ) 
6.12 ■ 


45.94 


3.85 


trace. 


4.19) 




8.28 • 


6.84 


1.45) 





100 97.88 



All these saline substances have their special functions to 
perform in the animal economy, and of each of them an unde- 
termined quantity daily escapes from the body in the perspira- 
tion, in the -urine, or in the solid excretions^ This quantity, 
therefore, must be daily restored by the food. 

2. It is interesting to remark how the mineral matter differs 
in kind in the different parts of the body. Thus, blood con- 
tains much soda and little potash — the former in the serum, 
the latter in the globules — the cartilages much soda and no 
potash, and the muscles much potash and little soda. So 
T^hosphate of lime is the earth of bones, and phosphate of 
magnesia the earth of the muscles. So also the presence of fluo- 
rine characterises the bones and teeth, and that of silica, the 
horny parts, hair and feathers of animals — while an abundance 
of iron distinguishes the blood and the hair. 

The distinction now noticed between the blood and the mus- 
cle is not brought clearly out by the analysis above given of 
the comparative composition of the saline matter of each. It 
is seen more clearly in the following comparison : — 



The mineral matter or ash 



Common salt, 

Chloride of potassium, 

Potash, 

Soda, 

Phosphoric acid, 

Oxide of ii'on, 

15* 



of ox blood 


of ox flesh 


contains, 


contains, 


per cent. 


per cent. 


47 to 51 


— 





10 


7-8 


36 


12 - 14 


— 


3 - 7 


35 


7 - 10 


1 



346 MINERAL MATTERS IN THE BODY. 

From the blood, therefore, as a common storehouse, each 
part obtains, by a kind of selection, the mineral matter which 
it specially requires. 

It has not yet been accurately determined by experiment 
how much saline matter must necessarily be excreted every 
day from the body of a healthy man, or in what proportions 
the different inorganic su])stances are present in what is ex- 
creted ; but it is satisfactorily ascertained, that without a cer- 
tain sufficient supply of all of them, the animal will languish 
and decay, even though carbon and nitrogen, in the form of 
starch and gluten, be abundantly given to it. It is a wise and 
beautiful provision of nature, therefore, that plants are so or- 
ganised as to refuse to grow in a soil from which they cannot 
readily obtain an adequate supply of soluble inorganic food, — 
since that saline matter, which ministers first to their own 
wants, is afterwards surrendered by them to the animals they 
are destined to feed. 

Thus, the dead earth and the living animal are but parts of 
the same system, — links in the same endless chain of natural ex- 
istences. The plant is the connecting bond by which they arc 
tied together on the one hand, — the decaying animal matter, 
which returns to the soil, connects them on the other. 

3. The bones of the animal are supplied with their mineral 
matter from the same original source, — the vegetable food on 
which they live. The dried bones of the cow contain 55 per 
cent of phosphate of lime with a little phosphate of magnesia, 
those of the sheep 10, of the horse 61, of the calf 54, and of the 
pig 52 lb. of these phosphates in every hundred of dry bone. 
All this must come from the vegetable food. Of this bone- 
earth, also, a portion — varying in quantity with the health, the 
food, and the age of the animal — is every day rejected. The 
food, therefore, must contain a daily supply, or that which 
passes off will be taken from the substance of the living bones, 
and the animal will become feeble. 

The importance of this bone-earth will be more apparent if 



THE FOOD SUPPLIES THE INCREASE. 34*1 

we consider, — First, that in animals the bones form not only a 
very important l)ut a very large part of their bodies. 
The body of a full-grown man contains 9 to 12 lb. of clean dry 
bone, yielding from 6 to 8 lb. of bone-earth. In the horse and 
sheep the fresh moist bone has been estimated at one-eighth of 
the live, or in the sheep to one-fifth of the dead weight, and 
to one-third of the weight of the flesh. Second, that in a 
growing sheep the increase of bone-earth amounts to about 3 
per cent of the whole increase in the live weight. And — 
Third, that every hundred pounds weight of live weight indi- 
cates 5 or 6 of phosphate of lime. 

It is kindly provided by nature, therefore, that a certain pro- 
portion of this ingredient of bones is always associated with 
the gluten of plants in its various forms, — with the fibrin of 
animal muscle and with the curd of milk. Hence man, from 
his mixed food, and animals, from the vegetables on which they 
live, are enabled, along with the nitrogen they require, to ex- 
tract also a sufficiency of bone-earth to maintain their bodies 
in a healthy condition. 

SECTION V. THE FOOD MUST SUPPLY THE WASTE OR INCREASE OF 

FAT IN ANIMALS. 

Every one knows that in some animals there is much more 
fat than in others, but in all a certain portion exists, more or 
less intermingled with the muscular and other parts of the 
body.* This fat is subject to waste, as the muscles are, and 
therefore must be restored by the food. All the vegetable sub- 
stances usually cultivated on our farms contain, as we have 
seen, (p. 306,) a notable quantity of fatty matter, which seems 
to be intended by nature to replace that which disappears na- 
turally from the body. 

* At Port Philip, in the boiling-houses, a Merino sheep of 55 lb. gives 
20 lb. of tallow, and of all weight above 55 lb. four-fifths are tallow. 



348 WASTE OF THE FAT. 

A full-grown animal, in which the fat may be regarded as in 
a stationary condition, requires no more fat in its food than is 
necessary to restore the natural loss. In such an animal the 
quantity of fatty matter found in the excretions is sensibly 
equal to that whiqh is contained in the food. 

But to a growing animal, and especially to one which is fat- 
tening, the supply of fatty matter in the food must be greater 
than to one in which no increase of fat takes place. It is in- 
deed held, that, in the absence of oil in the food, an animal 
may convert a portion of the starch of its food into fat, — may 
become fat while living upon vegetable food in which no large 
proportion of fatty matter is known to exist. And it can 
hardly be doubted, I think, that the organs of the living ani- 
mal are endowed with this power of forming in a case of emer- 
gency — that is, when it does not exist ready formed in the 
food — as much fatty matter as is necessary to oil the machinery, 
so to speak, of its body. But the natural source of the fat is 
the oil contained in the food it eats, and an animal, if inclined 
to fatten at all, will always do so most readily when it lives 
upon food in which oil or fat abounds. 

It does not however follow, because fat abounds in the food, 
that the animal should become fatter,— since if starch be defi- 
cient in the food, the fat containing no nitrogen, may be decom- 
posed and worked up for what may be called the purposes of 
respiration. This working up of the fat, already existing in 
the body, is one cause of the rapid emaciation and falling away 
of fat animals when the usual supply of food is lessened, or for a 
time altogether withheld. The fat is indeed considered by 
some as nothing more than a store laid up by nature in a time 
of plenty to meet the wants of respiration when a season 
of scarcity arrives, — that a fat animal is like a steam-frigate 
heavily laden with fuel, which it burns away during its voyage 
for the purpose of keeping up the steam. 

It is by reference to this supposed purpose of the fat of the 
body, and to the possibility of using it up for the purposes of 



PURPOSES SERVED BY THE FAT. 349 

respiration, that the benefits of repose, of shelter, of moderate 
warmth, of the absence of light, and even of a state of torpor, 
in conducing to the more speedy fattening of cattle and sheep, 
are explained. Exercise causes more frequent respirations, 
and hence a greater waste of that part of the food which should 
be laid on in the form of fat. Cold also has the same effect, 
since more heat must be produced in the interior of the animal 
— in other words, more frequent respiration must take place, in 
order to make up for the greater loss of heat by exposure to 
the extenial air. 

Thus, as was stated at the commencement of the present 
chapter, a study of the nature and functions of the food of ani- 
mals throws additional light upon the nature also and final uses 
of the food of plants. It even teaches us what to look for iu 
the soil — what a fertile soil must contain that it may grow nou- 
rishing food — what we must add to the soil when chemical 
analysis fails to detect its actual presence, or when the food it 
produces is unable to supply all that the animal requires. 

SECTION VI. SPECIAL WASTE IN THE PERSPIRATION OF ANIMALS, 

AND IMPORTANCE OF THIS FUNCTION. 

Animals perspire that they may live, and this function is as 
necessary to a healthy life as either breathing or digestion. 
The skin, like the lungs, gives off carbonic acid and absorbs 
oxygen. But it differs from the lungs in giving off a much 
larger bulk of the former gas than it absorbs of the latter. 
The quantity of carbonic acid which escapes varies with cir- 
cumstances. It is sometimes equal to a thirtieth, and some- 
times amounts only to a ninetieth part of that which is thrown 
off from the lungs. But exercise and hard labor increase the 
evolution of carbon from the skin, as it does from the lungs. 
In motion, the human body gives off nearly three times as 
much as when it is at rest ; while from a horse, when put to the 



350 CARBONIC ACID AND NITROGEN FROM THE SKIN. 

trot, the^ carbonic acid of the skin augments as mucli as an 
hundred and seventy times. (Gerlach.) 

Water is also given off from the skin as from the lungs, and 
every one knows that fat exudes from its pores and lubricates 
the surface of the body. The salt taste of the perspiration is 
an equally familiar proof that a portion, at least, of the saline 
matter derived from the waste and change of materials in the 
body escapes through this channel. 

Nitrogen also escapes from the skin. The quantity of nitro- 
gen in the food is a third or a fourth greater than that contained 
in the solid and liquid excretions. (Barral.) This third or 
fourth, therefore, is supposed to be given off by the organs of 
perspiration, the lungs and the skin. A cow or a horse is reck- 
oned to exhale by the skin and lungs about 400 grains of nitro- 
gen daily ; a man, perhaps, 100 ; and a sheep or pig 80 grains. 

(BOUSSINGAULT.) 

The functions of the skin, therefore, are very important ; and 
thus, in the practical feeding of animals, a healthy and clean 
condition of the skin must contribute not only to healthy growth, 
but to a profitable employment of vegetable produce in rearing, 
maintaining, and fattening them.* 

SECTION VII. FORMS IN WHICH THE SOLID MATTERS OF THE TISSUES 

ESCAPE IN THE URINE. 

The lungs throw off, in the form of gas or vapor, a large pro- 
portion of the matters which, after being taken into the stomach, 
have already served their purpose in the body. The kidneys 
remove the greater part of that which is derived from the 
destruction of the tissues. The solid excretions in man amount 

* Six pigs were put up together for seven weeks. Three were curry- 
comlaed and eared for — the other three left to themselves; the former 
three consumed five bushels of pease less, and had gained 2 stones 4 pounds 
more, than the uncurried three. The skins of pigs fed in the forest, in the 
season of the acorns, are white and shininjr. 



SALTS AND NITROGEl^ IN THE URINE. 351 

only to a fourteenth or an eighteenth of the whole food con- 
suraetl. 

In a state of health, the saline substances of the food escape 
for the most part in the urine. The mineral matter contained 
in that part of the solid excretions which has undergone diges- 
tion, consists chiefly of earthy salts and of iron. 

In man, and in our domestic animals, the nitrogen of the 
food and tissues is also separated from the blood by the kidneys, 
and is found in the urine. It is chiefly in the form of a sub- 
stance to which the name of urea is given. In birds, serpents, 
and insects, it is separated in the form of uric acid. The urine 
Toided by a healthy man in 24 hours, averages about 40 ounces, 
and contains about 150 grains of solid matter, which has served 
its purpose in the system. Of this solid matter, about 2t0 
grains consist of urea, 8 of uric acid, and 110 of mineral or 
saline matter. The -urine of the horse is richer in urea than 
that of the cow, and that of the cow than the urine of man. 
It is this urea which, during the fermentation or ripening of 
urine, becomes changed into ammonia. 

The urea and uric acid discharged daily in the urine of a 
healthy man, contains about half an ounce of nitrogen — to fur- 
nish which requires 3 ounces of dry gluten, albumen, or 
flesh. If so large a proportion of that which is most valuable 
in food, and which has been derived from the decay of the tis- 
sues of the body, is contained in the urine, it ought to be an 
important object to the farmer to contrive some method of re- 
turning it without loss to the soil, that it may aid again in rais- 
ing new vegetables as food for other animals. 

SECTION VIII. GENERAL BALANCE OF FOOD AND EXCRETIONS IN 

MAN. 

The general balance of the food taken into the human body 
and of the excretions of various kinds, has been thus represent- 
ed by M. Barral : 



352 BALANCE OF FOOD AND EXCRETIONS. 

Evenj 100 parts taken in, consist of— 
Food, solid and liquid, containing in all '75 per cent of water . 14.4 
Oxygen taken in by the lungs, 25. G 

100 
And are given off as — 
"Water perspired by the lungs and skin, . . . . 34.8 

Carbonic acid, do. do., 30.2 

Evacuations, solid and liquid, 34,5 

Other losses, 0.5 

100 

In general, the substances perspired are to the evacuations 
as 2 to 1. 

Of course, in an estimate of this kind, it is impossible accu- 
rately to put down the several quantities given off in the form 
of hair, nails, surface skin — both of the outer and inner parts 
of the body — &c., &c., all of which are constantly shed or 
cut, and as constantly renewed. It is useful, however, in show- 
ing generally the relation which the oxygen inspired bears to 
the other food which the stomach receives, and the proportion 
of the work of excretion performed respectively by the per- 
spiring organs, and by the organs of evacuation. 



SECTION IX. KIND OF FOOD REQUIRED BY ANIMALS AS INDICATED 

BY THE COMPOSITION OF THE BLOOD. 

A knowledge of the kind of food required by animals may 
be gathered, as we have seen, from the composition of tlie 
several parts of the animal body, and a study of the functions 
they perform. The muscles must be sustained ; therefore glu- 
ten, albumen, &c. — often popularly called muscular matter, 
must be eaten. The fat of the body must be renewed, and 
hence fat should be present in the food. And, as much carbon 
escapes from the lungs and skin, it seems natural, if not abso- 
lutely necessary, that starch or sugar should be introduced into 
the stomach with the view of supplying it. The mineral mat- 



WHAT THE BLOOD TEACHES. 353 

ter of the flesh, blood, and bones, must in like manner be pro- 
vided. 

Tlie study of the excretions indicates, besides, the quantity of 
food of each kind which ought to be consumed. The quantity of 
carbon evolved in the form of carbonic acid, of nitrogen in the 
forms of urea and uric acid, and of saline matters in the urine 
and solid excretions of a healthy man, afford a means of ap- 
proximating very nearly to the quantity of each which a suffi- 
cient food ought to contain ; but the excretions do not alone 
tell us in what forms the carbon, nitrogen, and saline matters 
are best suited to the wants of the animal. 

An examination of the blood gives us this latter information 
very clearly. The blood consists essentially, besides the water, 
of albumen, sugar, fat, and saline matter. The main purpose or 
object of the process of digestion is to form blood ; for out of 
the blood are drawn the materials necessary to the wants of the 
bones, and of the various tissues and fluids of the body. 
Those forms of vegetable or animal matter, therefore, must be 
best adapted for food, which most resemble the ingredients^ of 
the blood which is to be produced from them. These will give 
the digestive organs least trouble, or will be most easily 
digested. Thus we arrive again at the conclusion that a 
healthy, nourishing, and easily digestible food ought to contain 
gluten or albumen, sugar or starch — which, in the stomach, 
readily changes into sugar — fat either of animal or vegetable 
origin, and saline or mineral matters of various kinds. Of 
course, if the stomach of the animal be in an unhealthy condi- 
tion, the quality of the food may require to be adapted to its 
unnatural condition ; but this does not affect our general con- 
clusion. 

SECTION X. IMPORTANCE OF A MIXED FOOD. 

All these different modes of examining the question, there- 
fore, indicate not only the advantage but the necessity of a 



354 IMPORTANCE OF A MIXED FOOD. 

mixed food to the healthy sustenance of the animal body. 
Hence the value of any vegetable production, considered as 
the sole food of an animal, cannot be accurately determined by 
the amount it may contain of any one of those substances, all 
of which together are necessary to build up the growing body 
of the young animal, and to repair the natural waste of such 
as have attained to their fullest size. 

Hence the failure of the attempts that have been made to 
support the lives of animals by feeding them upon pure starch 
or sugar alone. These substances would supply the carbon 
perspired by the lungs and the skin ; but all the natural waste 
of nitrogen, of saline matter, of earthy phosphates, and probably 
also of fat, must have been withdrawn from the existing solids 
and fluids of their living bodies. The animals, in consequence, 
pined away, became meagre, and sooner or later died. 

So some have expressed surprise that animals have refused 
to thrive — have ultimately died, when fed upon animal jelly or 
gelatine alone, nourishing though that substance, as jpart of the 
food, undoubtedly is. When given in sufficient quantity, gela- 
tine might indeed supply carbon enough for respiration, with a 
great waste of nitrogen, but it is deficient in the saline in- 
gredients which a naturally nourishing food contains. 

Even on the natural mixture of starch and gluten which ex- 
ists in fine wheaten bread, dogs have been unable to live be- 
yond 50 days, though others fed on household bread, contain- 
ing a portion of the bran — in which earthy matter more largely 
resides — continued to thrive long after. It is immaterial whe- 
ther the general quantity of the whole food be reduced too low, 
or whether one of its necessary ingredients only be too much 
diminished or entirely withdrawn. In either case the effect 
will be the same — the animal will become weak, will dwindle 
away, and will sooner or later die. 

The skill of the feeder may often be applied with important 
economical effects to the proper selection and mixture of the 



VALUE OF OILY FOOD IN FATTENING. 355 

food he gives his animals generally, and at various stages of 
their growth. 

It has been found by experiment, for example, that food 
which, when given alone, does not fatten, acquires that pro- 
perty in a high degree when mixed with some fatty substance, 
and that those which are the richest in the muscle-forming in- 
gredients produce a comparatively small effect, unless they con- 
tain also, or are mixed with, a considerable proportion of fatty 
matter. Hence the reason why a stone of linseed has been 
found by some to go as far as two stones of linseed cake, and 
why the Rutlandshire farmers find a sprinkling of linseed oil 
upon the hay to be a cheap, wholesome, and fattening addition 
to the food of their cattle and horses. 

A Merino sheep of 55 lb. contains about 20 lb. of fat, but 
four-fifths of any subsequent addition consists of tallow, (p. 
34 1 note ;) hence w^e may infer that oily food should be profit- 
able in fattening sheep. To pigs the same remark appUes ; 
and, in practice, fat of any kind, animal or vegetable, is found 
to be a profitable addition to the food of these animals when 
they are to be fattened off. 



CHAPTER XXY. 

Feeding of animals continued. — Kind and quantity of food necessary to 
maintain a healthy man. — Prison dietaries. — Food required by other 
animals. — Practical value of the constituents of milk in feeding the 
growing calf — Effect of long-continued dairy husbandry upon the quality 
and produce of the soil. — On the growing of wool, and its effect upon 
the soil. — Of the practical and theoretical values of different kinds of 
food. — Relative proportions of food for man yielded by the same herbage 
in the forms of beef and milk. — Influence of circumstances in modifying 
the practical values of animal and vegetable food. — Concluding observa- 
tions. 

Practical experience sustains and confirms all the theoretical 
views, and the deductions, chemical and physiological, which 
have been advanced in the preceding chapter. To a few of 
these practical confirmations I shall briefly advert. 

SECTION I. KIND AND QUANTITY OF FOOD NECESSARY TO MAINTAIN 

A HEALTHY MAN. PRISON DIETARIES. — FOOD REQUIRED BY SHEEP 

AND CATTLE. 

The dietaries of prisons, and their effects on the bodily 
health and weight of the" prisoners, afford one of the simplest 
methods of testing the influence of kind and quantity upon the 
nourishing power of food. In such establishments — though 
open to the objection that the prisoners are in a state of un- 
usual restraint — experiments can be performed so much more 
accurately, and on so much larger a scale than elsewhere, as 
to make them worthy of a very considera^ble amount of confi- 
dence. 

An inquiry lately made into the comparative health and food 



SCOTCH PRISON DIETARIES. 



357 



of the inmates of the Scotch prisons, has aiforded very inter- 
esting materials for proving the necessity of a mixed food, and 
of a certain minimum proportion of that kind of food which is 
supposed especially to sustain the muscular and other tissues. 

In the course of the preceding chapter we have stated : 

1°. That a healthy man in ordinary circumstances voids daily 
about half an ounce of nitrogen in his urine alone, (p. 351.) 
To supply this he would require to consume three ounces of dry 
gluten, albumen, or flesh. 

2°. That altogether he gives off from the lungs, skin, and 
kidneys, about 350 grains, or five-sevenths of an ounce, to supply 
which he must consume about five ounces of the same rdaterials, 
(p. 342.) 

But in a state of temporary confinement, when not subjected 
to hard labor, this quantity may be safely diminished. Yet 
even here there is a limit below which it is unsafe to go. In 
the Scotch prisons the weight of food is given to prisoners con- 
fined for not more than two months, and not subjected to hard 
labor, is uniformly about 1 1 ounces, and the proportion of glu- 
ten or nitrogenous food contained in this is about four ounces. 
Where this proportion is maintained, the average general health 
and weight of the prisoners improves during their confinement. 
Where the contrary is the case, the weight diminishes, -and the 
health declines. This is shown in the following tabular view 
of the kinds and weight of food given in five of the Scotch 
prisons, and its effects upon the weight of the prisoners : — 



Jail. 


Food givex. 


Per-centage of pri- 
soners who lost 
weight. 


Nitrogenous. 


Carbonaceous. 


Total. 


Edinburgh, 

Glasgow, 

Aberdeen, 

Stirling, 

Dundee, 


4 oz. 
4.06 
3.98 
4.27 
2.75 


13 oz. 

12.58 

13.03 

13.4 

14 


17 oz. 

16.84 

17 

17.67 

10.75 


18 lost IJ lb. each 
32.66 4 

V 32 4.2 " 

50 4.35 " 



358 THEIR RESULTS. 

This table shows that, with the Edinburgh dietary and man- 
agement, 12 per cent of the prisoners either maintained or in- 
creased their weight, while only 18 per cent diminished in 
weight, and that only to the small extent of IJ lb. each. In 
Glasgow the result was less favorable, though even there, out 
of nearly 500 prisoners, only one-third diminished in weight. 

The same was the case at Aberdeen and Stirling ; so that 
in these three places the diet may be regarded as, on the whole, 
sufiicient. But in Dundee, one-half of the prisoners (50 per 
cent) lost weight during their short confinement ; and the cause 
is obvious, in the diminished proportion of mascle-forming food, 
which in this case was reduced to 2j, in place of four ounces. 

And it is an interesting fact, as marking the close connection 
between science and practice, that this deterioration in the 
quality of the diet was caused by the substitution of molasses 
for the milk, which had been previously distributed to the pri- 
soners along with their porridge of oatmeal. Milk is rich in 
nitrogenous food, while molasses contains none ; and the sub- 
stitution was immediately followed by a perceptible falling off 
in the health and weight of the prisoners. So general are the 
evils which may arise from ignorance or disregard of scientific 
principles in a single director or directing 'body. The appa- 
rently trivial substitution of molasses for milk brought weakness 
and want of health on the inmates of an entire prison. 

In the feeding of other animals, similar results follow from 
similar inattention to the requirements of animal nature. Of 
dry hay it has been found, in practice, that cattle and sheep 
require for their daily food — 



An ox at rest, 2 per cent 


of his live weight. 


. . at work, 2\ . . 




. . fatting, 5 


at first. 


.. half fat, 4^ .. 




when fat, 4 




Milch cow, 3 




Sheep, full grown, 3 J . . 





FOOD REQUIRED BY ANIMALS. 359 

In the case of the ox tlie daily waste or loss of muscle and 
tissue requires that he should consume 20 to 24 ounces of glu- 
ten or albumen, which, as may be calculated from the table 
given in a subsequent section, (p. 364,) will be supplied by any 
of the following weights of vegetable food^ : — 



Meadow hay, . 


. 20 lb. 


Turnips, 


120 lb. 


Clover hay, 


16 " 


Cabbage, 


70 " 


Oat straw, 


. 110" 


Wheat or other white grain, 


11 " 


Pea straw, 


12 " 


Beans or pease, 


6 " 


Potatoes, 


60" 


Oil-cake, 


4 " 


Carrots, . . 


*70" 







Or instead of any one of these, a mixture of several may be 
given, with the best results. But if the due proportion of ni- 
trogenous food be not given, the ox will lose his muscular 
strength, and will generally fail. So with growing and fatting 
stock of every kind, the proportion of each of the kinds of food 
required by the animal must in practice be adjusted to the 
purpose for which it is fed, as theory indicates, or actual money 
loss will ensue to the feeder. 

SECTION II. PRACTICAL VALUE OF SALINE AND OTHER INGREDIENTS 

OF MILK IN FEEDING THE GROWING CALF. 

In the course of the preceding section I have incidentally 
remarked, that the substitution of molasses for milk lowered 
the proportion of nitrogenous food in the Dundee prison diet, 
and rendered it insufficient for the healthy maintenance of the 
prisoners. The reason of this appears in the composition of 
milk, already given in a previous chapter. The consideration 
of milk as a natural food supplies us with another beautiful 
practical illustration of our theoretical principles, to which I 
shall briefly advert ; and I do so, not merely because of the 
light it throws upon the supply of nitrogen which a milk diet is 
fitted to yield, but because it so clearly illustrates another of 
the positions laid down in the preceding chapter, that the food 



860 MILK A TRUE FOOD. 

must supply, in kind and quantity, all the saline and earthy 
substances contained in the body. 

Milk is a true food. It contains sugar, casein, saline mat- 
ter, and fat — a portion of each of those classes of substances 
on which the herbivorous races live in the most healthy man 
ner. But the provision is very beautiful by which the young 
animal — the muscle and bones of which are rapidly growing — 
is supplied, not only with a large proportion of nitrogenous 
food, but also of bone-earth, than would be necessary to main- 
tain the healthy condition of a full-grown animal of fiqual size. 
The milk of the mother is the natural food from which its sup- 
plies are drawn. The sugar of the milk supplies the compara- 
tively small quantity of carbon necessary for the respiration of 
the young animal. As it gets older, the calf or young 
lamb crops green food for itself, to supply an additional portion. 
The curd of the milk (casein) yields the materials of the grow- 
ing muscles and of the organic part of the bones ; while along 
with the curd, and dissolved in the liquid milk, is the phosphate 
of lime, of which the earthy part of the bones is to be built 
up. A glance at the composition of milk will show how copi- 
ous the supply of all these substances is, — how beautifully the 
composition of the mother's milk is adapted to the wants of her 
infant offspring. Cow's milk consists in 1000 parts by weight 
of about — 

Butter, 21 

Cheesy matter, (casein,) 45 

Milk-sugar, 36 

Chloride of potassium^ and a little common salt, . 14 

Fhosjyhates, chiefly of Ume^ 24 

Other saline substances, 6 

Water, 882^ 

1000 

The quality of the milk, and consequently the proportions of 
the several constituents above mentioned, vary, as I have ex- 
plained in a preceding chapter, with the breed of the cow — 



DAIRY HUSBANDRY AFFECTS THE SOIL 361 

with the food on which it is supported — with the time that has 
elapsed since the period of calving — with its age, its state of 
health, and with the warmth of the weather;* but in all cases 
this fluid contains the same substances, though in different 
quantities and proportions. 

Milk of the quality above analysed contains, in every 10 gal- 
lons, 4| lb. of casein, equal to the formation of 18 lb. of ordi- 
nary muscle, — and 3 J ounces of phosphate of lime, (bone- 
earth,) equal to the production of t ounces of dry bone. But 
from the casein have to be formed the skin, the hair, the horn, 
the hoof, &c., as well as the muscle ; and in all these is con- 
tained also a minute quantity of the bone-earth. A portion of 
all the ingredients of the milk likewise passes off in the ordi- 
nary excretions, and yet every one knows how rapidly young 
animals thrive, when allowed to consume the whole of the milk 
which nature has provided as their most suitable nourish- 
ment. 



SECTION III. — EFFECT OF LONG-CONTINUED DAIRY HUSBANDRY UPON 
THE QUALITY AND PRODUCE OF THE SOIL. 

And whence does the mother derive all this gluten and bone- 
earth, by which she can not only repair the natural waste of 
her own full-grown body, but from which she can spare enough 
also to yield so large a supply of nourishing milk ? 

She must extract them from the vegetables on which she 
lives, and these again from the soil. 

The quantity of solid matter thus yielded by the cow in her 
milk is really very large, if we look at the produce of an entire 
year. If the average yield of milk be 3000 quarts, or 750 
gallons, in a year, (every 10 gallons of which contain bone- 
earth enough to form about 7 ounces of dry bone, ) then by the 

* In warm weather the milk contains more butter, in cold weather more 
cheese and suocar. 



363 BY REMOVING BONE-EARTH. 

milking of tlie cow alone we draw from her the earthy ingre- 
dients of 33 lb. of dry bone in a year. These are equal to 40 
lb. of (Common bone-dust,, or 3J lb. in a month. And these 
she draws necessarily from the soil. 

If this milk be consumed on the spot, then all returns again 
to the soil on the annual manuring of the land. Let it be 
carried for sale to a distance, or let it be converted into cheese 
and butter, and in this form exported — there will then be 
yearly drawn from the land from this cause alone a quantity of 
the materials of bones which can only be restored by the ad- 
dition of 40 lb. of bone-dust to the land. If to this loss from 
the milk we add only 10 lb. for the bone carried off by the 
yearly calf,* the land will lose by the practice of dairy hus- 
bandry as much bone-earth as is contained in 50 lb. of bone- 
dust — or in 45 years every imperial acre of land will lose what 
is equivalent to a ton of bones. 

After the lapse of centuries, therefore, we can easily under- 
stand how old pasture lands, in cheese and dairy countries, should 
become poor in the materials of bones — and how in such dis- 
tricts, as is now found to be the case in Cheshire, the applica- 
tion of bone-dust should entirely alter the character of the 
grasses, and renovate the old pastures. 

SECTION IV. — OF THE GROWING OF WOOL, AND ITS EFFECTS UPON 
THE SOIL. 

The rearing of wool affords another beautiful practical illus- 
tration, both of the kind of food which animals require i'or par- 

* It has been estimated that the proportion of bone in the — 
Horse, . . . . = .125of thehve weight. 
Sheep, old, (Merino,) . . == .125 of live, 20 of dead diO. 
= .33 nearly, of flesh and fat 
Pig, unfatted, . . . ^ = .1'? of live, .20 of dead do. 
And generally, that 100 hve weight indicate 2 to 3 of phosphoric acid ; but 
these proportions are, no doubt, subject to great variation. 



LONG GROWTH OF WOOL ON THE LAND. 363 

ticular purposes, and of the effect which a peculiar husbandry 
must slowly produce upon the soil. 

Wool and hair are distinguished from the fleshy parts of the 
animal by the large proportion of sulphur they contain. Per- 
fectly clean and dry wool contains about 6 per cent of sulphur, 
or every 100 lb. contains 5 lb. 

The quantity as well as the quality of the wool yielded by a 
single sheep varies much with the breed, the climate, the con- 
stitution, the food, and consequently with the soil on which the 
food is grown. The Hereford sheep, which are kept lean, and 
give the finest wool, yield only 1^ lb. ; but a Merino often 
gives a fleece weighing 10 or 11 lb., and sometimes as much as 
12 lb. 

The number of sheep in Great Britain and Ireland amounts 
to 30 millions, and their yield of wool to 111 millions of 
pounds, or about 4 lb. to the fleece. This quantity of wool 
contains 5 millions of pounds of sulphur, which is of course all 
extracted from the soil. 

If we suppose this sulphur to exist in, and to be extracted 
from, the soil in the form of gypsum, then the plants which the 
sheep live upon, must take out from the soil, to produce the 
wool alone, 30 millions of pounds, or 13,000 tons of gypsum. 

Now, though the proportion of this gypsum lost by any one 
sheep farm in a year is comparatively small, yet it is reasonable 
to beUeve that, by the long growth of wool on hilly land, to 
which nothing is ever added, either by art or from natural 
sources, those grasses must gradually cease to grow in which 
sulphur most largely abounds, and which favor, therefore, the 
growth of wool. In other words, the produce of wool is 
likely to diminish, by lapse of time, where it has for centuries 
been yearly carried off the land; and, again, this produce is 
likely to be increased in amount when such land is dressed with 
gypsum, or with other manure in which sulphur naturally ex- 
ists. Of course, this general conclusion will not apply to lo- 



364 



PRACTICAL AND THEORETICAL VALUES 



calities whicli derive from springs or other natural sources a 
supply of sulphur equal to that which is yearly removed. 



SECTION V.- 



-OF THE PRACTICAL AND THEORETICAL VALUES OF DIF- 
FERENT KINDS OF FOOD. 



From what has been stated in the preceding sections, it ap- 
pears, as the result both of theory and of practice, that dif- 
ferent kinds of food are not equally nourishing. This fact is of 
great importance, not only in the preparation of human food, 
but also in the rearing and fattening of stock. It has, there- 
fore, been made the subject of experiment by many practical 
agriculturists, with the following general results : 

1. If common hay be taken as the standard of comparison, 
then, to yield. the same amount of nourishment as 14 lb. of hay, 
experiments on feeding made by different persons, and in dif- 
ferent countries, say that a weight of the other kinds of food 
must be given, which is represented by the number opposite to 
each in the following table : — 



Hay, 


10 


Carrots, (white,) 


45 




Clover hay, 


8 to 10 


Mangold-wurtzel, 


. 35 




Green clover, 


45 " 50 


Turnips, 


50 




Wheat straw, 


40 " 50 


Cabbage, 


20 " 


30 


Barley straw, ■ 


20 " 40 


Pease and beans. 


3 " 


5 


Oat straw, 


20 " 40 


Wheat, . 


5 " 


6 


Pea straw, 


10 " 15 


Barley, . 


5 " 


6 


Potatoes, 


20 


Oats, . 


4 " 


1 


Old potatoes 


40 ? 


Indian corn, . 


5 




Carrots, (red) 


25 " 30 


On-cake, 


2 " 


4 



It is found in practice, as the above table shows, that 
twenty stones of potatoes, or three of oil-cake, will nourish an 
animal as much as ten stones of hay will, and 5 stones of oats 
as much as either. Something, however, will depend upon the 
quality of the sample of each kind of food used — which we 
know varies very much, and with numerous circumstances; and 
something also upon the age and constitution of the animal, 



OF DIFFERENT KINDS OF FOOD. 



365 



and upon the way and form in which the food is administered. 
The skilful rearer, feeder, and fattener of stock knows also the 
value of a change of food, or of a mixture of the different 
kinds of vegetable food he may have at his command — a sub- 
ject we have considered in a previous section, 

2. The generally nutritive value of different kinds of food 
has also been represented theoretically, by supposing it to be 
very nearly in . proportion to the quantity of nitrogen, or of 
gluten, which vegetables contain. Though this cannot be con- 
sidered as a correct principle, yet as the ordinary kinds of food 
on which stock is fed contain in general an ample supply of 
carbon for respiration, with a comparatively small proportion 
of nitrogen, these theoretical determinations are by no means 
without their value, and they approach, in many cases, very 
closely to the practical values above given, as deduced from 
actual trial. Thus assuming that 10 lb. of hay yield a certain 
amount of nourishment, then of the other vegetable substances 
it will be necessary, according to theory, to give the following 
quantities, in order to produce the same general effect in 



feeding 



Hay, . . 
Clover hay,* 
Vetch hay, 
"Wheat straw, 
Barley straw, 
Oat straw, 
Pea straw. 
Potatoes, 
Old potatoes, 
Turnips, 
Mangold- wurtzel, 



10 

8 

4 

52 

52 

55 

6 

28 

40 

60 

50 



Carrots, (red,). . 
Cabbage, . 
Pease and beans. 


35 

30 to 40 
2 to 3 


Wheat, 
Barley, 
Oats, 


5 
6 
5 


Rye, 
Indian com, 


5 
6 


Bran, 
Oil-cake, : 


5 

2 



If the feeder be careful to supply his stock with a mixture or 
occasional change of food — and especially, where necessary, 
with a proper proportion of fatty matter — he may very safely 
regulate, by the numbers in the above tables, the quantity of 



* Both cut in flower. 



366 ON WHAT TUE FATTENING PROPERTY 

any one which he ought to substitute for a given weight of any 
of the others — since the theoretical and practical results do not 
in general very greatly differ. 

3. As has been already stated, however, it is not strictly cor- 
rect that this or that kind of vegetable is more fitted to sustain 
animal life, simply because of the large proportion of nitrogen 
or gluten it contains; but it is wisely provided that, along with 
this nitrogen, all plants contain a certain proportion of starch 
or sugar, and of saline and earthy matter — all of which, as we 
have seen, are required in a mixture which will most easily sus- 
tain an animal in a healthy condition; so that the proportion 
of nitrogen in a substance may be considered as a rough jprao 
Heal index of the proportion of the more important saline and 
earthy ingredients also. 

4. It is very doubtful, however, how far this proportion of 
nitrogen can be regarded as any index of the fattening pro- 
perty of vegetable substances. If the fat in the body be pro- 
duced from the oil in the food, it is certain that the proportion 
of this oil in vegetable substances is by no means regulated by 
that of the gluten or other analogous substances containing ni- 
trogen. The stock farmer who wishes to lay on fat only upon 
his animals, must therefore be regulated by another principle. 
He must select those kinds of food, such as linseed and oil- 
cake, in which fatty matters appear to abound, or mix, as I 
have already said, (p. 354,) a due proportion of fat or oil with 
the other kinds of food he employs. 

But large quantities of fat accumulate in the bodies of most 
animals, only when they are in an unnatural, and, perhaps in 
some measure, an unhealthy condition. In a state of nature 
there are comparatively few animals upon which large accumu- 
lations of fat take place. A certain portion, as we have seen, 
is necessary to the healthy animal ; but it is an interesting 
fact, that as much as is necessary to supply this is present in 
most kinds of vegetable food. In wheaten flour it is asso- 
ciated with the gluten, and niny be extracted from it after the 



OF FOOD DEPENDS. 36T 

starch of the flour has been separated from the gluten by 
washmg with water, as akeady described (pp. 40 and 45.) In 
so far, therefore, as this comparatively small necessary quantity 
of fatty matter is concerned, the proportion of nitrogen may 
a^so be taken, without the risk of any serious error, as a prac- 
tical indication of the ability of the food to supply the natural 
waste of fat in an animal which is either growing in general 
size only, or is only to be maintained in its existing condition. 

While, therefore, it appears from the study of the principles 
upon which the feeding of animals depends, that a mixture of 
various principles is necessary in a nutritive food, it is interest- 
ing to find that all the kinds of vegetable food which are 
raised, either by art or by natural growth, are in reality such 
mixtures of these several substances — more or less adapted to 
fulfil all the conditions required from a nutritious diet, accord- 
ing to the state of health and growth in which the animal to 
be fed may happen to be. 

An important practical lesson on this subject, therefore, is 
taught us by the study of the wise provisions of nature. Not 
only does the milk of the mother contain all the elements of a 
nutritive food mixed up together — as the egg does also for the 
unhatched bird — but in rich natural pastures the same mixture 
uniformly occurs. Hence, in cropping the mixed herbage, the 
animal introduces into its stomach portions of various plants — 
some abounding more in starch or sugar, some more in gluten 
or albumen — some more in fatty matter — while some are natu- 
rally richer in saline, others in earthy constituents ; and out of 
these varied materials the digestive organs select a due propor- 
tion of each and reject the rest. Wherever a pasture becomes 
usurped by one or two grasses — either animals cease to thrive 
upon it, or they must crop a much larger quantity of food to 
supply from this one grass the natural waste of all the parts of 
their bodies. 

It may indeed be assumed as almost a general principle, that 
whenever animals are fed on one kind of vegetable only, there 



368 COMPARATIVE PRODUCE OF BEEF AND MILK. 

is a waste of one or other of the necessary elements of animal 
foodj and that the great lesson on this subject taught us by na- 
ture is, that by a judicious admixture, not only is food economis- 
ed, hut the labor imjposed ujpon the digestive organs is also materi- 
ally diminished. • 

SECTION VI. RELATIVE PROPORTIONS OF FOOD FOR MAN YIELDED BY 

THE SAME HERBAGE IN THE FORMS OF BEEF AND MILK. 

A curious economical question, in connection with the value 
of vegetable produce in feeding cattle, presents itself to us 
when we come to compare the proportions of human food which 
may be obtained from the same weight of herbage when cattle 
are fed with it for different immediate purposes. 

A ton of hay may be given to a bullock to be converted 
into beef. Another ton of the same hay may be . given to a 
cow to be converted iiito milk. Would the beef or the milk 
produced contain the larger supply of food for man ? We have 
rather imperfect data to rely upon in answerisg this question, 
but they lead us to very interesting results. 

1. According to Sir John Sinclair, the same herbage which 
will add 112 lb. to the weight of an ox, will enable a cow to 
yield 450 wine gallons, or 3600 lb. of milk. This milk will 
contain 160 lb. of dry curd, 160 lb. of butter, 180 lb. of sugar, 
and 18 lb. of saline matter, while the 112 lb. of beef will not 
contain more than 25 lb. or 30 lb. of dry muscle, fat, and sa- 
line matter together ; that is to say, the same weight of herb- 
age which will produce less than 30 lb. of dry human food in 
the form of beef, will yield 500 lb. in the form of milk. 

2. But this statement of Sir John Sinclair's is, I fear, not to 
be relied upon. We have another, however, something differ- 
ent, from Riedesel, a Continental authority. He says that the 
same quantity of hay will produce either 100 lb. of beef, or 
100 imperial gallons (1000 lb.) of milk. This quantity of 



CIRCUMSTANCES MODIFY 369 

milk contains only 150 lb. of dry food, but it is still five times 
as much as is contained in the beef. 

This statement of Riedesel is also to be received with hesita- 
tion ; but the subject is interesting and important, as well as 
curious, and is deserving of further investigation. Should the 
population of the country ever become so dense as to render a 
rigorous economy of food a national question, butcher-meat, if 
the al)ove data deserve any reliance — will be banished from 
our tables, and a milk diet will be the daily sustenance of al- 
most all classes of society. 

SECTION. VII. INFLUENCE OF CIRCUMSTANCES IN MODIFYING THE 

PRACTICAL VALUES OF ANIMAL AND VEGETABLE FOOD. 

The indications of theory, and the results of general prac- 
tice, in regard to the nutritive power of different vegetable 
substances, are modified by many circumstances which ought to 
be borne in mind. Whether fed for work, or for the produc- 
tion of flesh or milk, the eflfect of the food given to animals will 
depend partly on the kind, breed, and constitution of the ani- 
mal itself — on the general treatment to which it is subjected, 
and the place in which it is kept — on its size and state of health 
— and on the form in which the food itself is given. 

1. The breed or constitution, every feeder knows, has a great 
influence on the apparent value of food. Some breeds, like the 
improved short-horn, have a natural tendency to fatten, which 
makes them increase in weight more rapidly than other breeds, 
when fed upon the same food. And even in the same breed, 
the rapidity with which one animal lays on flesh will sometimes 
make it two or three times more profitable to the farmer than 
others which are fed along with it. 

2. Warmth and shelter cause the same amount of food to go 
farther, as do also gentle treatment and the absence of glaring 
light. Sheep have produced double the weight of mutton 
from the same weight of vegetable food, when fed under shel- 



3 to THE PRACTICAL VALUE OF FOOD. 

ter, and kept undisturbed and in the dark. It is probably from 
this beneficial influence of warmth that, in the North American 
states, a difference of 25 per cent is observed in favor of the 
spring and summer over the winter feeding of the pigs upon 
similar food. 

3. The form in which the food is given is of no less importance- 
Grass newly cut goes farther than after it is made into hay; 
and the opinion is now becoming very generally prevalent, 
that steamed, boiled, or otherwise prepared food, is more whole- 
some for .cattle, and more economical to the feeder, than the 
same food given in a dry state. 

In the case of horses, the difference between the practice of 
giving all the food dry and uncut, and that of giving all the 
hay cut with the oats and beans crushed, and an evening meal 
of steamed food, is such as to effect a saving of nearly one- 
third. Thus, the same waggon horses which consumed 8J 
bushels of oats per week, and 14 stones of hay, when given 
uncut, uncrushed, and uncooked, were kept in good condition 
by 2J bushels of oats, 8 stones of hay, and *I lb. of linseed 
when the grain was crushed, the hay cut into half-inch chaff, 
and the linseed with a little bean-meal and cut hay made into 
a steamed meal-feed ii^the evening.* 

4. The malting and sproibting of harky is by many practical 
men considered to increase its nutritive qualities. It is certain 
that, when mixed with boiled potatoes to the extent of three 
or four per cent, and kept warm for a few hours, bruised malt 
produces a prepared food which is much relished by milch 
cows, and is profitable to the dairy-man. There is reason to 
believe that similar mixtures with other kinds of food would 
produce similar beneficial effects. 

Mr. Hudson, of Castle Acre, feeds his farm-horses on 12 lb. of 
sprouted barley a-day, besides their fodder ; and this, on his 

* The dry feeding being — hay 12 lb., with oats and beans 14 lb. ; the 
steamed feed — hay 3 lb., beans 3 lb., linseed 1 lb. — Caird's English Agri- 
culture, p. 346. 



CONCLUDING REMARKS. 311 

light land, keeps them in good condition. It is prepared by 
steeping the barley for 24 honrs, and then putting it into a 
heap and turning it over for five days.* 

5. The souring of food of all kinds has, by almost universal 
consent, been found to make it more jn'ofitable in the feeding 
and fattening of pigs. It makes them fatten faster, and gives 
a firmer and whiter flesh. 

Many other circumstances also modify the real practical 
value of food, and cause it to produce results different from 
those indicated by its chemical composition. But to those, 
want of space does not permit me here to advert. 

SECTION VIII. CONCLUDING REMARKS. 

In the little work now brought to a close, I have presented 
the reader with a brief, but I hope plain and familiar sketch of 
the various topics connected with Practical Agriculture, on 
which the sciences of Chemistry, Geology, and Chemical Phy- 
siology are fitted to throw the greatest light. 

We have studied the general characters of the organic and 
inorganic elements of which the parts of plants are made up, 
and the several compounds of these elements Avhich are of the 
greatest importance in the vegetable kingdom. We have exa- 
mined the nature of the seed — seen by what beautiful pro- 
vision it is fed during its early germination — in what forms the 
elements by which it is nourished are introduced into the cir- 
culation of the young plant when the functions of the seed are 
discharged— and how earth, air, and water, are all made to 
minister to its after-growth. We have considered the various 
chemical changes which take place within the growing plant 
during the formation of its woody stem, the blossoming of its 
flower, and the ripening of its seed or fruit, — and have traced 
the further changes it undergoes, when, the functions of its, 

* Oaird's English Agriculture, p. 168. 



312 CONCLUDING REMARKS. 

short life being discharged, it hastens to serve other purposes, 
by minghng with the soil, and supplying food to new races. 
The soils themselves in which plants grow, their nature, their 
origin, the causes of their diversity in mineral character, and 
in natural productiveness, have each occupied a share of our 
attention — while the various means of improving their agricul- 
tural value by mechanical means, by manuring or otherwise, 
have been practically considered, and theoretically explained. 
Lastly, we have glanced at the comparative worth of the va- 
rious products of the land as food for man or other animals, 
lind have briefly illustrated the principles upon which the feed- 
ing of animals, and the relative nutritive powers of the vegeta- 
bles on which they live, and of the parts of animal bodies 
themselves, are known to depend. 

In this short and familiar treatise I have not sought so much 
to satisfy the demands of the philosophical agriculturist, as 
to awaken the curiosity of my less instructed reader, to show 
him how much interesting as well as practically useful informa- 
tion Chemistry and Geology are able and willing to impart to 
him, and thus to allure him in quest of further knowledge and 
more accurate details to my larger work,'^ of which the present 
'exhibits only a brief outline. 

* Lectures on Agricultural Cliemistry and Geology. 



THE END. 



ALPHABETICAL AND ANALYTIOAL 



INDEX 



A. 




Analysis of organic parts of 










plants. 


14 


Acm, Carbonic, . . 18, 32 




" of barley, wheat, oats. 




" Humic, 


21^ 




beans, rye, corn, 




" Geic, .... 


21 




linseed, potato, and 




" Crenic, 


22 




turnip. 


64 


" Apo-Crenic, . 


. 22 




" of guano, , 


208 


" Nitric, 


29 




" of experiments with 




" Sulphuric, 


33 




salts of ammonia, 


225 


" Pliosplioric, 


34 




" of carbon and nitro- 




" Pectose, pectic. 


44 




gen taken in food 




" of milk, how produced. 


327 




and respired, 


21'? 


Acorn, composition of, 


289 




" of soils. 


263 


Agriculture, a .chemical art, 


133 




" of water, 


274 


Albumen, . . .46 


342 


Aquafortis, (nitric acid,) 


29 


Alumina, .... 


56 


Ash 


, of wood and grain. 


6 


Ammonia, its properties, . 


26 


(( 


of wheat and oat straw. 




" nitrate of. 


30 




wheat leaves, oats, oak 




" salts of, as manures. 


222 




wood, animal substan- 




" carbonate ofj 


223 




ces, and bones. 


•7 


" sulphate of; 


224 


li 


quantity of left by plants. 


59 


*' salts of, experiments 




u 


" of in different plants, 59 


with, 


225 


11 


quality of. 


64 


Animals, organic parts of. 


14 


u 


of grains, table of, 


64 


" main visible functions 




a 


quantity of depends on the- 




of; . . . 


337 




soil, ... 63 


, 67 


" respiration of. 


338 


u 


of straw, table of. 


68 


" carbon given oflT by. 


339 


u 


of crab apple tree. 


67 


" bones of. 


346 


" 


of wheat, table of, 


68 



kind of food required by, 3 5 9 



of wood and straw. 



232 



3U 



INDEX. 



Ash, of bushels of oats, barley, 

and rice, . . 233 

" of peat and coal, . 234 

Atmosphere, composition of, .82 



B. 



Barley, composition of, . 284 

" malting quahties of, . 285 

" feeding qualities of, 286 

" varying qualities of, 290 

" oil in 100 lbs. of; . 307 

Bean, composition ofj . .288 

Beef, and milk, ... 368 

Blood, kind of food required, as 

indicated by the, . 352 
" what it teaches, . 353 
Body, muscular parts of the, . 341 
*' mineral matter in the, 345 
Bran, value of, . . .176 
Bromides, ... 59 
Bromine, ... .58 
Bones, dry, 6 per cent, phospho- 
rus, ... 14 
" composition of and value 

as manure, . . 192 

" to dissolve with acid, 194 

" experiments with, . 195 

Buckwlieat, composition of, 287 

Butter, quality of varies, . 322 

" composition of, . 323 

'' preservation of, . 324 

" why it becomes rancid, 325 

" coloring of, . . 326 



0. 



Cabbage, composition of, . 300 
Carbon, . . . . 218 

Carbonate of potash and soda, 226 
" of magnesia in lime- 
stone, . . 252 
Casein, . . . .46, 342 
Cauliflower, qualities of, . 301 
Chalk, iu Alabama, . .114 



Charcoal, uses of, . . 181 

Cheese, manufacture of, . 331 
" quality of, . .332 

" varieties of, . . 333 
" .cream, cream and milk, 
whole or full milk, 
half milk, skimmed 
milk, . . 334 

" whey, butter-milk, veg- 
etable and potato, 325 
Chemistry, what it will do for 

agriculture, . 1 
Chlorides, how formed, . 58 

Chlorine, . . . .57 

Churning, . . . 319 

Clay, influence of air, frost, and 

water on, . . 142 

" sinks in the soil, . 151 

" and earth burned, . 269 

" cause of the mechanical 

and chemical action of, 270 
Clover, red and white, what soils 

they like, . . 130 
" hay, oil in 100 lbs. of 307 
Coal dust and coal tar, . 183 

Cocoanut cake, . . .178 
Corals, shell-sand, marls, . 253 
Corn, Indian, composition of, 287 
" oil in 100 lbs. of . 307 
Cream, composition of, . .319 
Crops, why one may grow well 

where another fiiils, . t2 

" rotation of necessary, 72,132 

Curd, why it separates, . 329 



Dairy husbandry, effects of on 

the soil, . . .361 

Digestion, effects of animal, 217 

Draining, benefits produced by, 137 

" of light soils, , 138 

" summaryof advantages 

of; . . . 142 

" depth of; . . . 142 

Dung, value of, . . . 218 

' ' of full-grown animals, 219 



INDEX. 



3t5 



E. 

Experiments, importance of, 



Farmer, object of the practical, 1 
Fat, waste of in animals, . 347 
" pur^joses served by, . 349 
Fermentation, of dry vegetable 

matter, . 174 

" loss of weight by, 175 

Fibrin, composition of, . 342 

Fluorine, . . . . 59 

Food., quantity yielded by an 

acre, ... 308 
" must repair daily waste 

in animals, . . 341 
" must supply saline and 

earthy matters. . 344 
" importance of a mixed, 353 
" vakie of oily, in fatting, 355 
" kind and quantity neces- 
sary to maintain a heal- 
tliy man, , . 356 

" given prisoners, . . 357 
" required by sheep and 

cattle, . . . 358 

" practical and theoretical 

value of, . . 364 

" on what its fattening prop- 
erties depends, . 366 
" animal and vegetable, 369 
" practical value of, . . 370 
" form in which it is given, 370 
" the souring of, . .371 
Fork, use of in loosening subsoil, 150 
Fruits, composition of, . 302 

" effects of soil on their 

quality and flavor, 303 



G. 



Gas, Hydrogen, 
" Oxygen, 
" Nitrogen, 



Geology, what it will do for agri- 
culture, . . 1 
" its relations to agricul- 
ture, . . 8, 102 
" value of to the farmer, 88 
Gelatine, ... 34, 342 
Gluten, .... 342 
Grass, laying down land to, 159 
" how land is improved by 

laying down to, . 160 
" roots of remaining in the 

soil, . . . 161 
" natural changes, . . 166 
Guano, varieties of, . . 205 
" fertilizing effects o^ 206 
" composition of, . 208 
" permanence of action of, 209 
" adulteration of, . 210 
" how to select good, 211 
" national value of, . 212 
" artificial, how to pre- 
pare, . . 248 
Gypsum, taken from the soil by 

wool-growing, . 363 



H. 



Hay and straw, . . 309 

" time of GUI ting affects quan- 
tity and quality ot; . 303 
" clover, oil inlOO lbs.' of, 307 
" meadow, oil in 100 lbs. of, 307 
Hemp, poppy and cotton cakes, 178 
Horn and hoof parings as ma- 
nure, . . . 119 
Hydrogen, ... 9 



Illustrations — 

Burning the soil, . . 6 

procuring hydrogen gas, 9, 10 

" oxygen gas, 11 

» carbonic acid, 18, 19, 20 

burning hydrogen gas, . 24 

procuring phosphoric acid, 34 

pores on the leaf of garden 

balsam, . . .37 



376 



Illustrations — 

procuring starch, 



40 



starch, ghiten and fat in grain, 41 
procuring chlorine, . 57 

stratified and unstratified 

rocks, ... 84 

section of coast Hnc, . 91 

of different soils, . 94,95,98 

of drifts, . . .113 

Inorganic bodies, . . 6 

" matter carried off in crops, 69 

Insects, as a manure, . . 189 

Iodine, .... 58 

Iodides, .... 59 

Iron, oxide or rust of, . 140 

Irrigation, . . .272 



Land, improvement of by feed- ^on 

ing sheep. 

Leaves, how they fertilize . 158 

" of turnips, potatoes, &c., 171 

" of trees, nutrition of, 301 

Lime, . . . .55, 155 

" Nitrate of, . . . 30 

" sinlvs in the soil, 150, 259 

" phosphate ofj in animals, 252 

" burning and slaking of, 254 

" effects of exposure of, to 

the air, . . . 255 

" effects of burning, . 256 

" quantity usually applied, 257 

" visible improvements by, 258 

" why it must be repeated, 258 
" crops and rains carry it 

away, . . . 259 
" chemical effects of, . 260 
" exhausting eftects of, 265 
Limestones and chalks, composi- 
tion of; . . 2^0 
" benefits of burning, 255 
Xinsoed, and linseed cake, . 287 
" oil in 100 lbs. of, . 307 
Lungs, carbon given off by, 339 
" the, actually feed the 

body, . . .340 



M. 

Magnesia, . . . .55 
" nitrate of, . . 30 

" carbonate of, in lime- 
stone and chalk, 252 
Maize, (Indian corn), composi- 
tion of, . . . 287 
Malt-dust, . . . .177 
Manure, accurate knowledge 

of, . . . 3 

" artificial, why necessary, 71 
" what is a, . . 168 
" use of vegetable, . .168 
" relative fertilizing and 
money values of dif- 
ferent vegetable, 184 
" sea-weed, uses of, as a, 169 
" saw-dust and bran, as a, 176 
" brewers' grains, malt 

and rape dust, . 177 
" hemp, poppy, and cotton 

cakes, . . . 178 
" peat, peat compost, and 

tanners' bark, . 178 
" fermented and charred 

peat, . . 179, 180 
" charcoal, soot, and coal- 
tar, ... 181 
*' immediate and perma- 
nent effects of vege- 
table manures, . 186 
" animal, fish, . . 187 
" blood as a, . . 189 
" skin, bone, hair, wool, 190 
" nitrogen in animal, 191 
" cow, liorse, and pig, 204 

" droppings of birds, 205 
" relative values of dif- 
ferent animal, . 213 
" difference in animal and 

vegetable, . .215 
" causes of difference be- 
tween animal and ve- 
getablej . . 216 
" saline, whj'- required by 

the soil, . . 236 
" how to determine the 

value of sahne, . 237 



INDEX. 



3tt 



Manure, saline, circumstances 
under wliieh they 
are to be used, . 238 
" saline, specific action of 

on plants, . . 240 
" saline, action of on par- 
ticular parts and kinds 
of plants, 
" sulphates and nitrates, 

mixed, 

" mixed, promote growth, 
and prevent mil- 
dew, . . 24G, 247 
" soil can be restored 
, by, . . . 

'* influence of, on wheat 
and other corn 
crops, 
Manuring, green, 

" with dry vegetable 
matter, 
Matter, organic diminishes in 

the soil. 
Milk, properties and composition 



241 



243 



267 



278 
171 



174 



266 



of, . . . 312, 


360 


" influence of breed on, 


314 


*' of form and constitution 




on, ... 


315 


" of kind of food on, 


316 


" of soil on, 


317 


" adulteration of. 


318 


" the whole may be churn- 




ed, ... 


320 


" time required for churn- 




ing, 


321 


" why it becomes sour, 


326 


" sugar of, acid of, . 


326 


" acid of, how produced. 


327 


" curdling of; and casein, 


328 


*' rich in nitrogenous food, 


358 


" value of saline ingredients 




in, . 


359 


" a true food, . 


360 


" removes bone-earth from 




the soil, . 


362 


" proportions of food yielded 




by, .. . . 


368 


uahroom, .... 


301 



N. 



Night-soil, and poudrette, . 203 
Nitrogen, . . . 12, 218 
" necessity of, to the plant, 15 
*' forms in which it enters 

the roots, . . 52 

" in animal manures, 191 
" necessary to the wlieat . 

crop, . . . 225 
" exhaled by the skin and 

lungs, . . 350 



0. 



Oats, composition of, . . 282 

" when tb cut, . . 305 

" and straw, oil in, . .307 

Oil, in grain, hay and root 

crops, . . . 306 

Organic bodies, ... 6 

Oxygen, . . . . 9, 32 

" ' the body fed by, . 340 



Paring and burning, . . , 268 
Pea, composition of, . . 288 
" and bean, varying quaU- 

ties ot; . . . 291 

Peat, use of, . . . - 178 

" fermented, . . . 179 

" charred, as an absorbent, 180 

" ashes, composition of. 235 

Perspiration, waste in animal, 349 

Phosphate, how formed, 34, 57 

" ammoniaco-magne- 

sian, . . 202 
" of lime (and na- 
tive,) . 229, 230 
" experiments with 

mixed, . . 245 
" of lime in limestone, 252 

Phosphorus, .... 9 
Physiology, what it will do for 

agriculture, . 1 



378 



INDEX. 



Plants, organic parts of, . 13, 14 
" structure of stem, root 

and leaf of; . . 36 

" functions of roots of, 37 

" " of tlie leaf of, 37 

" " of the stem of, 39 

" substances of which they 

consist, . , 39 

" structure of their seeds 41 
^* fatty substance of, . 44 
" waxes and resius of, 45 

" growtli of; . . . 4V 

" woody matter of, . 49 
" source of earthy matter of 54 
" select the soils On which 

tliey prefer to grow, 130 
" sicken on some soils, 132 
Plow, subsoil, how it acts in 

improving the soil, 147 
" results of experiments 

witli, . . 149, 150 
Plowing, deep, how it im- 
proves tlie soil, 158 
" chemical eflects o^ 153 
Potash, . . . .55 

" nitrate of, . . 30 

Potato, average composition 

of, . . 294, 295 

" influence of variety on, 29G 
" effect of manures on, 297 
" effects of keeping, and 

frost on, . . 298 

Poudrette, . . . .203 



R. 



Rags, woollen, as manure, 191, 214 
Rain, efiects of on the soil, 144 
" causes the air to be re- 
newed, . . . 144 
" warms the under soil, 144 

" equalizes the temperature, 145 
" carries down soluble sub- 
stances, . . , 145 
" washes out noxious mat- 
ters, . . . .145 
" brings down fertilizing 

substances, . . 146 



Rain, mechanical action of, 162 
Rape-dust, as manure, . 177 
" cake value of, . 289 

Rennet, action of, . . 329 
Respiration, effects of, . .216 
Rice, composition of, . . 287 
Rivers, English and Indian, 277 
Rocks, crumbling of; . . 82 
^' constancy in mineral 
character among the 
stratified, . . 85 

" the crag, ... 92 
" the plastic clays and 

chalks, . . 93 

" the green sand, . . 94 
" the wealden formation, 95 
" the upper, middle, and 
lower oolite and the 
leas, . . .96 

" the new red sand-stone, 
the magnesian lime- 
stone, and the coal 
measures, . . 97 

" the mill-stone grit, the 
mountain limestone, 
and old red sandstone, 98, 99 
" the upper and lower Sil- 
urian system, . 100 
" the Cambrian, mica slate 

and gneiss systems, . 101 
" granite, composition of, 104 
" quartz, felspar, trap and 
hornblende composi- 
tion of, . . 105, 106 
" rotten rock, marl, . 107 
Rye, composition of; . . 287 
" varying quality of, . 291 



Sal-ammoniac, 


. 224 


Salt, common. 


227 


Salts, Glauber's, . 


. 228 


" Epsom, 


228 


Sap, cause and motion of, 


. 39 


" changes as it ascends, . 


48 


Saw-dust, value of, 


. 176 



INDEX. 



379 



Science and practice, close con- 
nection between, . . 358 
Sea-weed and straw, ashes of, 321 
Seeds, structure of, . • 41 

" germination of, . . 4T 
" steeping of in salts of 

ammonia, • . 224 
Sheep, sulphur in their wool, 3G3 

Silica, 55 

Silicate of potaeh and soda, 228 
Skin, carbonic acid and nitrogen 

from, . • • 350 
Soda, .... 55 

" nitrate of, . . • ^^ 

" and potash, carbonate of, 226 
" sulphate of (Glauber's salts), 328 
" sulphate and nitrate of, 

mixed, . . .543 

Soils, benefit from analysis 

'of, . . 3,122,123 
" organic part of, . . "^^ 

" inorganic part of, . _ . ^^ 
" saline or soluble portion of, 16 
" earthy or insoluble portion 

of, .... '^^ 
" sandy, loamy, and peaty, 18 
" diversities of, and subsoil, 19 
" origin of, . • • ^2 
" caiise of the diversity of, 82 
" diflerences of, on stratified 

roclvs, ... 89 

" density, and absorbent 

power of, . . Ill 
" evaporative power and 

shrinkage of, . • 118 
" absorption of moisture of 
the air by, and tempera- 
ture of, ... 119 
" chemical composition of 121 
" fertile and barren com- 
pared, . . . 124 
«' causes of the fertility of 

black, . . .129 

" connection between and 

plants, . . • -'•^^ 
" general improvement of, 135 
" two classes of, . .136 
" liable to be burned up, 139 



Soils, improvement of by mixing, 154 
»' " by planting, 156 

u " by laying down 

to grass, 152 
Soot, uses of, . . • • 189 
Starch and gluten, quantities of 

in crops, . 305 

Straw, ashes of, . . • 231 
" and hay, . . .301 
" atfected by the time of 

cutting, . . 304 

Subsoil, importance of, . . 80 

" effects of bringing it up, 152 

Sulphate, how formed, . 34, 56 

" of ammonia, . .224 

» of potash, . . 221 

» of soda, (Glauber's 

salts,) . . 228 
" of magnesia, (Epsom 

salts,) . . 228 

" of iron, (green vitrei,) 228 

" of hrae, (gypsum,) 229 

" of soda with nitrates, 243 

Sulphur, . . . 9, 56, 363 

Sulphuric acid, ... 33 

" influence of on crops, 196 

Super-phosphate of lime, 34, 230 



Table — 

" of sugars, ... 43 

" of the ash of plants, 59,60 
" of hornblende and felspar, 106 
" of soils, . . 125, 128 
" of experiments with tur- 
nips, barley, and po- 
tatoes, . . 149, 150 
" of dry food and farm-yard 

dung, . . . 115 
" of peat compost, . . 180 
" of farm-yard manure and 

guano, . . . 180 
" of wheat dressed wath soot, 182 
" of the relative fertilizing 
and money values of 
diflerent vegetable ma- 
nures, . . 184,185 



380 



INDEX. 



Table of horn and bones, . 192 

" of experiments with gu- 
ano, 

" of comparison of man- 
nures, . . 213, 

" of carbon and nitrogen 
taken in the food and 
respired, 

" of experiments with sahs 
of ammonia, . 

" of composition of peat 
ashes, 

" of mixed sulphates and 
- nitrates, 

" of mixtures promoting 
growth, . 

^' and preventing mildew, 

" of artiiicial guano, 

" of composition of lime- 
stone, 

" of lime carried away by 
crops, 

" of the effect of equal quan- 
tities of mo.nures. . 

" of composition of wheat, 280-1 

" of composition of the 

oat, . . 282 

" of composition of bar- 
ley, . . 284 

" of composition of rye. 



207 



214 



2n 

225 

235 

244 

246 
247 

248 

251 

259 
279 



283 



285 
287 
287 
287 
287 



of " rice, 
of " corn, . 
of " buckwheat 
of " tne bean and 

pea, 
of " linseed and 

cake, . 
of " the acorn, 
of " the turnip, 
of " the potato, 
of " the cabbage 
of '* the cauliflower, 301 
of " hay, straw, 

leaves, 301 
of ' fruits, . 302 

of relative quantities of 
starch and gluten in 
cultivated crops, . 305 



288 

289 
290 
294 
294 
300 



Table of proportion of oil in 

plants, . . . 307 
" of quantity of food yield- 
ed by an acre of land, 308 
" of composition of that 

food, . . . 309 
" of composition of milk, 313 
319 
322 



" 01 cream, 

" of " butter, 
" of " fibrin, or 

muscle, 342 

" of " saline matter 

in the body, 344 
"of " mineral mat- 
ter, . 345 
" of " food given in 
Scotch pris- 
ons, . 357 
" of food required daily by 

animals, . . 358 

" of composition of cow's 

milk, . . . 360 
" of value of different kinds 

of food, ... 364 
Taffo, Chinese, night-soil, . 204 
Tanks, for liquids, construction 

of, ... 200 

" Tanners' bark, . .178 
Trees, why different kinds suc- 
ceed each other. . 131 
" the peach in New Jersey, 131 
" effects of the Scotch fir 
and beech on pasture 
land, . . . 156 
" action of, iii improving the 

soil, ... 158 

Trenching, how it improves the 

soil, . 150, 153 
Tull, Jethro, experiments of, 153 
Turnip, composition of, 294, 295 



U. 

Urine, means of preserving and 

applying it, . . 1 9t 
" of man, . . .198 
" of the pig and cow, 199 



/j » -i-'- 



INDEX. 



381 



Urine, sulphated, . . 201 

" solid matters escape from, 

the, . . . .350 
" salts and nitrogen in, 351 

Urate, how to form a, . 201 



V. 



Vegetable products, analyses of, 3 

Vitriol, oil of, • . . . 9 

" green, sulphate of iron, 2'28 



W. 



Water, composition of, . 25 
" its relations to vegetable 

life, ... 26 

" differs in natural virtue, 275 
" effects of difierent springs 

of, . . . 276 

Weeds, fire, what soils they like, 130 



Weeds sea, uses of, 


172 


" special action of, 


173 


" sea, ashes of and straw. 


231 


Wells, in Alabama, 


114 


Wheat, average composition of. 


280 


" influence of climate on, 


280 


" influence of the kinds of 




manure on, 


281 


" varying quality of, 


291 


" when to cut it. 


304 


" flour, oil in, 


307 


Winds, effects of in improving 




the soil, 


164 


Wool, growing, its effects on the 




soil, 


362 


" varied by climate and 




food, 


363 


" and hair, 5 per cent, sul- 




phur, . 


14 


Worms, earth, effect of as labor- 




ers, . 


163 


" quantity of, 


164 



MAP m 



LIBRARY OF CONGRESS 



DD0Eb71fl'^34 



